World No. 1 Jannik Sinner steels past Jan-Lennard Struff to reach Halle semifinals

In his first tournament since claiming the No. 1 ranking, Jannik Sinner has played clutch tennis to begin the grass-court swing and improved to 3-0 against Jan-Lennard Struff, defeating his German rival, 6-2, 6-7 (1), 7-6 (3) to reach the Terra Wortmann Open semifinals.

The reigning Australian Open champion was pushed to three sets in his first two matches of the week but looked much stronger on Friday, breezing through the opening set and ultimately advancing in a third straight three-setter after two hours and 29 minutes on OWL Arena.

Sinner is also playing his first event since reaching the semifinals at Roland Garros, where he suffered a narrow defeat to eventual champion Carlos Alcaraz in five sets. A former Wimbledon semifinalist, the 22-year-old looked poised to make a seamless transition onto grass but has endured tough opposition from his opening round against Tallon Greikspoor.

After rallying from a set down to defeat the in-form Dutchman, 6-7 (8), 6-3, 6-2, the top seed faced another three-setter when he lost a second-set tiebreaker to Fabian Marozsan before defeating the Hungarian, 6-4, 6-7 (4), 6-3. Despite the extra time spent on court, Sinner began proceedings against Struff with clear confidence, having twice beaten the unseeded German in 2024—both times in straight sets.

The 34-year-old played a tough match of his own to kick off his Halle campaign, winning a 12-10 final-set tiebreaker against Luciano Darderi before making quicker work of former No. 3 Stefanos Tsitsipas on Thursday. Though he reached a final on grass last summer in Stuttgart, Struff struggled early against Sinner, who swept the opening set in 30 minutes flat behind two breaks of serve.

Sinner threatened to carry that momentum early in the second set, overpowering Struff off the ground to engineer a break point in the fourth game. Struff saved it with an ace and three more two games later as the set headed towards a tiebreaker.

Struff made a move as the Sudden Death got underway, sending Sinner tumbling as he scored the first mini-break and raced through the first four points. Up 5-1 at the change of ends, Struff served and volleyed to set point and converted as Sinner erred off the backhand side.

Sinner kept creating chances in the decider, jamming Struff at the net off a backhand return to earn two break points in the ninth game. Struff fought both off with strong serving and twice forced Sinner to serve to stay in the match. Sinner replied strong as the match reached its thrilling climax, opening up a 3-0 lead in the final-set tiebreaker.

A dominant volley followed by a well-struck return set up four match points for the top seed, who converted the second when Struff netted a backhand approach.

Standing between Sinner and a fourth final of the season will be the winner of the last-eight encounter between American Christopher Eubanks and China's Zhang Zhizhen, who upset former No. 1 Daniil Medvedev earlier in the week.