Alexander Bublik earned the biggest win of his career as he stunned World No.1 Jannik Sinner in the second round of the Halle Open. Bublik smashed 36 winners to claim a 3-6, 6-3, 6-4 win to reach the quarter-finals of the tournament.

Bublik lost the opening set in only 26 minutes but broke the Italian’s serve in the sixth game of the second set. The Kazakhstan player was able to bring his best to the court and hit the right shots in the last two sets.

“We are tennis players and we try to win every match we play but it is a special one,” Bublik said. “I had never beaten a No. 1 in the world. It is an accomplishment.”

Bublik also smashed 15 aces against Sinner and lifted his serve to move ahead in the tournament.

“I kept serving. I tried to be clutch. I tried to get back whatever I [could]. He is an unbelievable player and I was not thinking that I could beat him,” said Bublik, who is the first player since last August to defeat Sinner other than Carlos Alcaraz. “But I had a few chances and executed them well. I kept serving. I had better chances than at Roland Garros. I stayed there, tried to return as much and serve aces, so the ball doesn’t come back and it worked really well.”

Bublik, the 2023 Halle Open champion, was happy with the way he served against Sinner.

“I had an amazing forehand to break in the third set and then I kept serving,” Bublik added. “On grass, if you lose your serve, it is maybe tough and I am a guy who doesn’t lose a lot of serves. I just kept serving and putting him in uncomfortable positions and it worked well.”

Bublik will next take on Tomas Machac in the quarterfinals on Friday.