Matteo Berrettini earned the biggest win of his career by beating top seed and world No. 2 Alexander Zverev in three sets at the Monte Carlo Masters in Monaco.

Berrettini served for the match up 5-4 in the third set, but he was broken after making four basic errors. Undeterred, he broke Zverev in the next game, including a 48-shot rally at 40-40, before serving out a 2-6, 6-3, 7-5 win.

It is a first triumph over a top-two player for Berrettini, 28, and only the 11th top-10 win of his career. It follows his win over Novak Djokovic in Doha, Qatar in February,

For Zverev, the loss confirms the end of his opportunity to overtake Jannik Sinner as world No. 1, while the Italian serves his three-month anti-doping ban.

After easing through the first set, the quality of his groundstrokes plummeted in the second. His passive play, coupled with the slower surface, allowed Berrettini to protect his weakness on his backhand groundstroke. He could either run around it and hit a forehand, because Zverev’s groundstrokes weren’t rushing him, or he could use his slice, waiting for a ball short enough to attack.

In the 48-shot rally that proved to be the defining point, Berrettini hit four run-around forehands, four backhand slices, and five backhand groundstrokes. The fifth groundstroke, hammered down the line when Zverev did not see it coming, put the German on defense for the first time in 46 shots. A meek forehand slice gave Berrettini the short ball he was hunting, and he hammered it away for a winner.

Zverev is now 6-6 since the end of the Australian Open, where Sinner ruthlessly dispatched him in the final. By his own admission, the start of the clay-court season does not suit him well, as it takes him time to ease on to the surface on which he is most dangerous. For his opponents, each passing loss will dim that sense of danger.

Berrettini will play Jiri Lehecka of the Czech Republic or compatriot Lorenzo Musetti in the third round.

(Clive Brunskill / Getty Images)