BERLIN, Germany (AFP)--World No. 1 Aryna Sabalenka cruised into the Stuttgart Open semi-finals on Saturday while two-time champion Iga Swiatek lost to Jelena Ostapenko for the sixth time in as many meetings.

Sabalenka reached the last eight without striking a ball following a bye and walkover, and took time to find her rhythm against Elise Mertens before wrapping up a 6-4, 6-1 victory.

Mertens broke for a 4-3 lead in the opening set but Sabalenka hit back right away and reeled off nine of the final 10 games to power into a semi-final showdown with Jasmine Paolini.

“Finally I played my match,” Sabalenka said. “Never happened before that I play the first match on Saturday... Happy with the variety of the game I brought today on the court. Yeah, I think it was very decent game.”

“I had a week to practice on these courts, so I felt pretty comfortable,” she added.

There was a strange incident in the first set when Sabalenka took a photograph of a disputed ball mark after disagreeing with an “out” call on her shot when she was break point down.

Sabalenka received a warning for unsportsmanlike conduct from the chair umpire but quickly regrouped to take control of the match, putting the distraction to one side.

“When I gave her a handshake, there was a very interesting look and a very strong handshake. Never had it before,” Sabalenka said after her post-match exchange with Miriam Bley.

Sabalenka will next play fifth seed Paolini after the Italian swept aside fourth-ranked Coco Gauff 6-4, 6-3. Sabalenka beat Paolini in straight sets en route to the title in Miami last month.

A beaten finalist three times in a row from 2021 to 2023, Sabalenka has never won in Stuttgart.

However, the Belarusian won’t have to contend with Swiatek — who beat her in the last two of those finals — after the second-ranked Pole suffered another defeat by the unpredictable Ostapenko.

Ostapenko, ranked 24 in the world, won 6-3, 3-6, 6-2 in a clash of past and present French Open champions.

Swiatek has now lost all six matches against the Latvian, with Saturday’s defeat the first on clay.