Manchester United and Liverpool have largely had the pick of the Premier League's best players over the years - although there is often a power struggle between the two clubs.
Fifteen years ago, United were top of the tree and the more attractive proposition. These days, Jurgen Klopp's Reds are the outfit young players would rather join.
Liverpool learnt the hard way that the Red Devils were the team to play for back in 2009 when they came close to signing a young Cristiano Ronaldo from Sporting Lisbon, only to miss out on him by the skin of their teeth.
Back when Gerard Houllier was Reds boss, with Phil Thompson as his number two, Ronaldo was offered to the club by his then-agent Paul Stretford.
Ronaldo was valued at a measly £4million and Thompson was flown out to Portugal to conduct a scouting mission.
The Reds assistant met with Tony Henry, who worked with Stretford, while in Portugal to thrash out the finer details of a deal.
Thompson recently recalled to Paddy Power: "We actually went and had a look at him because he was being offered to a lot of clubs by his agent Paul Stretford, and we were being offered him as well. There was Manchester United, I remember being linked, Newcastle as well, and people were wanting him.
"I went to see the last game of the season over there [in Portugal] and we chatted. That was on Sunday, on Monday I arrived back in Liverpool, went into training, we were sitting there, and I said to Gerard Houllier, 'This boy's a player, he's great!' He'd been offered to everybody for £4m. He wanted £1m over the four years of his contract and it would have quite easily been done."
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Liverpool were understandably convinced they had won the race to sign Ronaldo only to later discover they had been beaten to the punch by Man United.
Houllier ordered Thompson to find out what had transpired in the immediate aftermath of discovering that the Red Devils had moved ahead of them in the transfer race, and to see whether Liverpool could still resurrect a deal.
Thompson continued: "Next thing, it comes up on the screen on the strap at the bottom of Sky Sports News, 'Cristiano Ronaldo signs for United - £12.2m'.
"Gerard Houllier said, 'What the heck's gone on there, Phil? I thought it was £4m? I thought it was up for debate!' He said, 'Get on to the agent and find out why!' I went over there with a guy called Tony Henry who worked with Paul Stretford and I rang him and he said, 'Phil, when I got off the plane I got a phone call and got told 'You're off the deal'.'
"You can make up your own minds what happened there but that was close, but he's done alright for himself, hasn't he?"
Thompson has previously discussed Liverpool missing out on Ronaldo, telling The Athletic that he and Houllier "nearly choked" on their food when they realised Man United had won the transfer race.
Fast forward thirteen years and a power shift brought about by United's demise following the departure of Sir Alex Ferguson and Liverpool's rise, with Klopp finding a winning formula, and the Reds were suddenly the more attractive proposition.
And just like Liverpool did in 2003, United found this out the hard way when they came very close to signing Mane from Southampton.
At the time, Mane had agreed to join the Red Devils, but Klopp got revenge on Man United for the Ronaldo deal and signed the Senegal international from under their noses.
Mane recalled the story in an interview with the Daily Telegraph back in May: "I have to say, I was really close to going to Manchester United. I had the contract there. I had it all agreed. It was all ready, but instead, I thought, 'No, I want to go to Liverpool.'
"I was convinced to go with (Jurgen) Klopp's project. I still remember the first time I got the call from Klopp. He said, 'We have a big project at Liverpool and I want you to be part of it.'
"Then he asked what position I wanted because he could see at Southampton I played on the right side and I used to play on the left. I said I prefer left, and then he said, 'But (Philippe) Coutinho is on the left!'
"So I said, never mind, I will play on the right. I could see myself in all the positions."
