BAD HOMBURG, Germany (AFP) — 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.

“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.