The new millennium brought big transfers across Europe, with one club in particular shaking up the market.
Florentino Perez was elected as Real Madrid president in the summer of 2000 and his policy of signing "Galacticos" saw some huge deals completed in the first half of the decade.
And although Perez resigned after a bad run of results in 2005, his return in 2009 brought a new wave of spending in the Spanish capital.
There was significant spending at Barcelona, too, while the top clubs in Italy and England also splashed the cash to bring in marquee signings.
Here, a look at the most expensive transfers from the 2000s...
32. Ronaldinho
Ronaldinho's arrival at Barcelona changed everything for the Catalan club, bringing about an upturn in fortunes as results improved on the pitch and the big prizes were won in the years ahead.
Barça paid Paris Saint-Germain €32.24 million for the brilliant Brazilian, who led the Blaugrana to back-to-back La Liga titles and a Champions League crown, as well as winning the Ballon d'Or and two FIFA World Player of the Year prizes.
31. Xabi Alonso
Xabi Alonso's €34.5 million signing made him only the fourth-most expensive arrival at Real Madrid in the summer of 2009 – behind Cristiano Ronaldo, Kaka and Karim Benzema.
The stylish Spain midfielder joined from Liverpool and went on to become a fan favourite at the Santiago Bernabeu, where he won one La Liga title, two Copas del Rey, a Supercopa and a Champions League before moving to Bayern Munich in 2014.
30. Nicolas Anelka
Nicolas Anelka's time at Real Madrid was a disappointment overall as he hit just seven goals in 31 appearances, but Los Blancos still managed to sell the French forward for a decent price.
Having paid €35 million to sign Anelka from Arsenal in 1999, Madrid sold the striker to his former club Paris Saint-Germain for €34.5m the following summer. In a season-and-a-half at PSG, he scored just 18 goals in 56 appearances.
29. Arjen Robben
Real Madrid spent €35 million to bring Arjen Robben to the Santiago Bernabeu in 2007 following the Dutch winger's impressive spell at Chelsea.
But Robben ended up spending just two seasons at Madrid before moving to Bayern Munich in 2009 as Florentino Perez returned to Real as president and made a series of big signings – including Cristiano Ronaldo and Kaka.
28. Karim Benzema
Karim Benzema signed for Real Madrid as part of a huge investment in 2009 following the return of Florentino Perez as president.
Benzema arrived in a €35 million deal from Lyon and went on to enjoy an unbelievable career with Los Blancos, winning five Champions League titles and becoming the club's second-highest scorer (with 354 goals) behind Cristiano Ronaldo in 14 seasons at the Santiago Bernabeu.
27. Dani Alves
Courted by many of the world's biggest clubs during his time at Sevilla, Dani Alves ended up signing for Barcelona in a €35.5 million transfer in 2008.
Alves struck up an excellent understanding with Lionel Messi on the right and was a key player in Pep Guardiola's great side. The Brazilian right-back spent eight seasons at Camp Nou overall, winning 23 trophies, before leaving for Juventus in 2016. He returned for another short spell in 2021/22.
26. Javier Saviola
Javier Saviola became the most expensive player in Barcelona's history when he signed from River Plate in a €36 million transfer in 2002.
The Argentine striker scored 70 goals in 168 games for the Catalan club but had spells at Monaco and Sevilla during his time at Camp Nou and moved to Barça's fierce rivals Real Madrid for free when his contract expired in 2007.
25. Lilian Thuram
A Coppa Italia and UEFA Cup winner with Parma, Lilian Thuram was also part of the triumphant France side at the 1998 World Cup.
After five seasons at Parma, Thuram followed team-mate Gianluigi Buffon to Juventus in a deal worth around €36.15 million. The defender won two Serie A titles in a five-season spell with the Bianconeri and was a Champions League finalist in 2003.
24. Filippo Inzaghi
After finding himself behind David Trezeguet at Juventus, Filippo Inzaghi was sold to AC Milan for a fee of around €36.15 million in 2002.
Inzaghi went on to spend 11 seasons at San Siro, scoring 126 goals in 300 games for Milan. The striker won two Champions League titles with the Rossoneri, among a number of trophies, and was part of Italy's World Cup-winning squad in 2006.
23. Gabriel Batistuta
Gabriel Batistuta is best remembered for his time at Fiorentina, but the Argentine striker left Florence for Roma in the summer of 2000.
Although he only spent two-and-a-half seasons at the Stadio Olimpico following his €36.15 million move, Batistuta played a significant role as Roma won the Scudetto in 2000/01. After a short spell at Inter on loan, he finished his career in Qatar.
22. Wayne Rooney
When Newcastle United made a bid to buy Wayne Rooney from Everton in 2004, Manchester United sprung into action and signed the England striker in a €37 million deal.
Rooney went on to overtake Sir Bobby Charlton as United's all-time top scorer, netting 253 goals in 559 games for the Red Devils. He was also instrumental as United won a string of trophies, including five Premier League titles and the Champions League in 2008. Rooney returned to Everton in 2017 and retired in 2021 after spells with DC United and – as player-manager – at Derby County.
21. David Beckham
David Beckham moved to Real Madrid for €37.5 million in the summer of 2003, joining Luis Figo, Zinedine Zidane and Ronaldo in a team of "Galacticos".
But it turned out to be a turbulent time for Madrid as a bad run of results saw the club miss out on a major trophy at the end of the 2003/04 season. Beckham had to wait until his final season to win La Liga and scored 20 goals in 155 games overall before joining LA Galaxy in 2007.
20. Michael Essien
Michael Essien made over 250 appearances for Chelsea between 2005 and 2013, winning two Premier League titles, four FA Cups and a Champions League crown in that time.
The Ghanaian, who joined from Lyon in a deal worth around €38 million, spent the 2012/13 season on loan at Real Madrid and later moved to AC Milan before winding down his career in Greece, Indonesia and Azerbaijan.
19. Dimitar Berbatov
After two successful seasons at Tottenham, Dimitar Berbatov left the north London club to sign for Manchester United in 2008.
Spurs had also accepted an offer from Manchester City and the saga seemed to drag on all summer before the transfer was finally completed on deadline day for a fee of £30.75 million (€38m). The Bulgarian spent four seasons at Old Trafford and scored 56 goals for United, winning two Premier League titles in that time.
18. Didier Drogba
Didier Drogba signed for Chelsea in 2004 as part of a big summer spree following the arrival of Jose Mourinho as manager at Stamford Bridge.
The Ivory Coast striker joined from Marseille in a €38.5 million deal and scored 157 goals in his eight seasons at the club, winning a series of trophies along the way – including the club's maiden Champions League in 2012. He returned for another season in 2014/15.
17. Hernan Crespo
When Ronaldo left Inter to join Real Madrid in the summer of 2002, the Nerazzurri signed Hernan Crespo as the Brazilian's replacement in a €40 million transfer.
Crespo arrived from Lazio in a player-plus-cash agreement, which saw Bernardo Corradi move the other way. The Argentine striker scored just seven goals in 18 Serie A appearances and joined Chelsea the following summer, but later returned to Inter for a second spell between 2006 and 2009.
16. Rui Costa
After seven successful seasons at Fiorentina, Rui Costa joined Serie A rivals AC Milan in the summer of 2001 for €41.32 million.
The elegant Portuguese midfielder went on to win a number of trophies at San Siro, including the Champions League in 2003, but was not quite as important as he had been in Florence. He returned to former club Benfica in 2006.
15. Juan Sebastian Veron
Much was expected of Juan Sebastian Veron following the Argentine midfielder's €42.6 million transfer from Lazio to Manchester United in 2001.
Veron had been one of the finest players in his position during spells at Sampdoria, Parma and Lazio, but did not quite live up to expectations at Old Trafford and was sold to Chelsea for a significant loss in 2003.
14. Robinho
Robinho became Manchester City's first marquee signing following the takeover of the Abu Dhabi United Group, joining on the same day the buyout was completed.
The Brazilian forward arrived in a €43 million move from Real Madrid in 2008, but would only spend a season and a half at City before a brief loan back at former club Santos and a move to AC Milan for just €18m in the summer of 2010.
13. Andriy Shevchenko
One of the world's best strikers during his time at Dynamo Kyiv and AC Milan, Andriy Shevchenko signed for Chelsea in a £30.8 million (€43.88m) deal in 2006.
In and out of the Blues side in two difficult seasons at Stamford Bridge, the Ukrainian scored 22 goals in 77 appearances for the west London club and returned to AC Milan in 2008 before ending his career back at Dynamo.
12. Pavel Nedved
Pavel Nedved was signed by Juventus from Lazio in the summer of 2001 as a replacement for Zinedine Zidane.
Nedved joined Juve in a €45 million deal and went on to spend eight successful seasons in Turin. The Czech Republic midfielder helped the Bianconeri to the Champions League final in 2003, won four trophies and stayed after the Calciopoli scandal saw the club relegated in 2006. He also claimed the Ballon d'Or in 2004.
11. Ronaldo
Ronaldo was the world's most expensive player on two occasions in the 1990s and the Brazil forward's move from Inter to Real Madrid was also one of the biggest transfers of the 2000s.
Fresh from winning the World Cup with Brazil and finishing as the top scorer in Japan and Korea, Ronaldo returned to Spain in a €45 million deal as Real Madrid's latest "Galactico" signing. He scored 104 goals in 177 games for Los Blancos, but won just three trophies before leaving for AC Milan in January 2007.
10. Rio Ferdinand
Rio Ferdinand became the world's most expensive defender when he moved from Leeds to Manchester United for €46 million in the summer of 2002.
The former West Ham centre-back went on to feature in over 450 games for the Red Devils, winning six Premier League titles and a Champions League in 12 seasons at Old Trafford. He briefly joined QPR in 2014, but retired at the end of the season.
9. Gaizka Mendieta
Gaizka Mendieta was one of the best midfielders in the world in the late 1990s and early 2000s and helped Valencia to back-to-back Champions League finals in 2000 and 2001.
Wanted by a number of Europe's biggest clubs, Mendieta signed for Lazio in a €48 million transfer in the summer of 2001, making him the sixth-most expensive player of all time in that moment. But the move failed to work out and after loans at Barcelona and Middlesbrough, the Basque joined Boro permanently in 2004.
8. Gianluigi Buffon
Gianluigi Buffon became the world's most expensive goalkeeper when he moved from Parma to Juventus in 2001 for €51.88 million.
It was also one of the biggest transfers of all time, but turned out to be money well spent as Buffon went on to make over 650 appearances for the Bianconeri before joining Paris Saint-Germain in 2018. Buffon won 10 Serie A titles with Juve and also the World Cup with Italy. He returned to Turin for a second spell in 2019.
7. Hernan Crespo
Hernan Crespo briefly became the world's most expensive player in the summer of 2000 as he left Parma for Lazio in a transfer totalling €56.81 million.
The player-plus-cash deal saw the Argentine striker move to Rome as Matias Almeyda and Sergio Conceicao went in the opposite direction. Crespo scored 48 goals in 73 games for Lazio in two seasons, but won only a Supercoppa Italiana. He joined Inter in 2002.
6. Fernando Torres
Fernando Torres broke the hearts of Liverpool fans when he left Anfield for Chelsea in a €58.5 million deal in January 2011.
The Spain striker had been an idol with the Reds and was never quite able to recapture that form at Chelsea, scoring just 45 goals in 172 games for the west London club. He did win trophies with the Blues, though, including the Champions League in 2012.
5. Luis Figo
Florentino Perez promised he would sign Luis Figo from Barcelona if he won the Real Madrid presidential elections in the summer of 2000.
Figo had signed an pre-agreement with Perez and was unable to get out of it when he was elected, paving the way for one of the most shocking transfers in football history as Los Blancos paid the winger's €60 million release clause to take him to the Santiago Bernabeu. On one visit to Camp Nou with Los Blancos, a pig's head was famously thrown at the Portuguese.
4. Kaka
Hundreds of AC Milan fans protested against the sale of Kaka to Real Madrid outside the Italian club's headquarters, but the Brazilian joined Los Blancos for €67 million in June 2009.
Part of a huge summer spree which also saw Cristiano Ronaldo, Karim Benzema and Xabi Alonso brought to the Santiago Bernabeu, Kaka struggled with fitness problems during his time at Real Madrid and only showed his best in glimpses during his four seasons in Spain. He returned to Milan in 2013.
3. Zlatan Ibrahimovic
Barcelona had just won the treble in 2009 but felt the need for a big signing after Real Madrid's huge summer spree following the return of Florentino Perez.
So Zlatan Ibrahimovic arrived from Inter in a deal which eventually cost the Catalan club €69.5 million – €46m for the Swedish striker plus €20m as Samuel Eto'o moved the other way, with some additional fees on top. Despite a promising start, Ibra fell out with Pep Guardiola and returned to Italy with AC Milan the following summer.
2. Zinedine Zidane
Florentino Perez passed a napkin to Zinedine Zidane at a gala in Monaco. On it was written a question: "Do you want to come [to Real Madrid]?"
Zidane wrote "yes" in English and soon, the French midfielder was on his way to the Santiago Bernabeu in a world-record €77.5 million deal in 2001, which was not broken for another eight years. Zidane hit a wonderful winner for Los Blancos in the Champions League final the following May.
1. Cristiano Ronaldo
Cristiano Ronaldo had been wanted by Real Madrid for some time, but finally left Manchester United for the Santiago Bernabeu in the summer of 2009 for a world-record fee.
Madrid paid United €94 million to secure the Portuguese superstar in a huge summer spree following the return of Florentino Perez. Ronaldo went on to score an incredible 450 goals in 438 games for Los Blancos in nine seasons at the club and was instrumental as the club won four Champions League titles in that time.
*All figures via Transfermarkt
