After losing the first set 3–6 and battling cramps in the third, Sinner rallied to win 6–3, 7–5
The win extended Sinner's unbeaten streak on indoor hard courts to 21 matches
This is Jannik Sinner's second Vienna Open title of his career
Jannik Sinner clinched his second Vienna Open title after overcoming cramp to win a three-set encounter with second seed Alexander Zverev.
Sinner, who won the title in 2023 against Daniil Medvedev, repeated the trick two years on as he came from a set down to clinch a 3-6 6-3 7-5 triumph.
The Italian struggled to find his groove in the early stages of the first set as Zverev raced into a 4-1 lead and went on to claim the set.
However, the world number two responded in the second set.
Sinner was able to get the better of Zverev's serve immediately and had little trouble from then on in ensuring the match would go the distance.
The decisive break in the decider went in Sinner's favour for a 6-5 lead, when Zverev sliced a backhand long, enabling the top seed to serve out the win and claim a fourth title of 2025.
"It feels amazing," said Sinner. "It was such a difficult start in this final for me. I went a break down, had some chances in the first set but couldn't use them.
"He was serving very well, but I just tried to stick there mentally and play my best tennis when it came.
"The third set was a bit of a rollercoaster, but I was feeling the ball very well at times, so I tried to push, and I'm very happy, of course, to win another title. It's very special."
Elsewhere, Joao Fonseca's remarkable rise continued as he claimed his biggest title yet by beating Alejandro Davidovich Fokina 6-3 6-4 in Basel.
Data Debrief: Sinner's hard-court run rolls on
Sinner is arguably the best hard-court player on the ATP Tour, and he has now won 21 successive matches on the surface.
This success also marks his 21st career title, too, while he is 48-6 for the season, ahead of the big tournaments still to come in the form of the Paris Masters and ATP Tour Finals.
Fonseca, meanwhile, became the first Brazilian to win a title at ATP 500-level or higher since Gustavo Kuerten triumphed in Cincinnati in 2001.
