Former world No 1s Naomi Osaka and Victoria Azarenka both advanced to the second round in the Wimbledon warm-up tournament at Bad Homburg on Monday.
Japan's Osaka battled past Serbian qualifier Olga Danilovic 7-6 (8/6), 7-6 (7/4) as Belarusian Azarenka beat Germany's Laura Siegemund 6-2, 6-2.
Azarenka, 35, next meets Poland's Iga Swiatek in the second round.
Osaka fired 16 aces with Danilovic hitting 10 in a big-serving battle which lasted just over two hours.
triumph in the tiebreakers!@naomiosaka takes down Danilovic 7-6(6), 7-6(4)!#BadHomburgOpen pic.twitter.com/8DlOlWuLVC
— wta (@WTA) June 23, 2025
"It's my first grass-court win of the year, so I'm really excited about that," said Osaka, a wildcard to the main draw.
"I think I have potential (on grass), but everyone else is also really good.
"I can never take it for granted, the wins. Just super excited that I won today."
The victory halts Osaka's three-match losing streak after Rome, the French Open and Berlin as she continues her comeback from maternity leave last year.
The four-time Grand Slam winner advances to a second-round meeting with fifth seed Emma Navarro of the United States.
Osaka saved four break points, while Danilovic fought off six, with the Japanese player coming through two tight tie-breaks.
Osaka came back from 4-2 down in the first-set breaker, using her backhand to force an error on her second set point.
Danilovic started the second set with three consecutive aces.
In the tiebreak Osaka challenged a called ace by Danilovic and the review showed the ball just out. Danilovic then double-faulted, and Osaka took a 3-1 lead.
A smash gave Osaka a 6-4 advantage and double match point which she wrapped up with a forehand winner on the next point.
Two-time Australian Open champion Azarenka had to qualify for this week's main draw, but eased past wild card Siegemund.
Simply Flawless ✨@vika7 takes out Siegemund in straight sets 6-2, 6-2 to set up a meeting against Swiatek.#BadHomburgOpen pic.twitter.com/fHCqsHN9OF
— wta (@WTA) June 23, 2025
Croatian Donna Vekic lost to Diana Shnaider in last year's Bad Homburg final, but she reversed that result on Monday.
Vekic saved all four break points she faced to sweep past the sixth seeded Russian 6-3, 6-3.
She next plays Czech Linda Noskova who beat Australian Ajla Tomljanovic 6-3, 6-2.