Bayer Leverkusen thrashed Werder Bremen 5-0 on Sunday to win the Bundesliga with five fixtures to spare and end Bayern Munich's recent dominance in the competition.
Bayern had won the title for the past 11 seasons and Leverkusen had never been champions in their entire 120-year history. In fact, the club had even been cruelly nicknamed "Neverkusen".
They had famously come close in 2001/02, finishing as runners-up in the Bundesliga, while losing in the final of both the Champions League and the German Cup.
But 22 years on, those painful memories were wiped away as Bremen were swept aside by a penalty from Victor Boniface, a special strike from Granit Xhaka and a Florian Wirtz hat-trick.
The big win saw Leverkusen clinch the title with five games to spare, having led Bayern by 13 points at the start of the day and extended that gap back to 16 by beating Bremen.
"This is a very special moment for the club," Alonso said after the match. "After 120 years, to win the Bundesliga for the first time is something extraordinary. The players really performed, they were a top team together. I am so proud of all of them. For me, it's an honour to work here.
"Finally, we can say Bayer Leverkusen is a German champion. It's a huge honour for all of us."
And he added: "This is a moment to enjoy and a huge success for this club. The first title is always special for everyone. So to be part of this history feels incredible."
But Leverkusen can still achieve a lot more in the remainder of the season, with two trophies left to play for. Plus the possibility of securing a historic achievement.
Alonso's side have not been beaten in any of their matches so far this term and can complete an invincible campaign in the Bundesliga if they avoid defeat in their next five fixtures.
After five straight victories in the DFB-Pokal, Leverkusen can also win that competition if they beat Kaiserslautern in the final on May 25. And in the Europa League, Alonso's side will look to seal a place in the semi-finals this week as they take a 2-0 lead into the second leg at West Ham.
An invincible season in all competitions? Now that would be special.
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