BERLIN - Four-time Grand Slam winner Naomi Osaka tumbled out of the Berlin Open first round on Tuesday after Russia's Liudmila Samsonova battled from a set down to win 3-6 7-6(3) 6-4 on Tuesday.

It was a disappointing start to the former world number one's grass season, with Wimbledon in just under two weeks. The 27-year-old Japanese had won her first title in May in almost two years following a maternity break.

Osaka, who had reached the third round of the Australian Open in January before retiring injured, also lost in the first round of the French Open.

After a strong start from Osaka, Samsonova battled back in the second set to clinch it in a tiebreak with the Russian world number 20 firing 11 in the first two sets.

Osaka was 40-0 up on her opponent's serve at 5-5 but could not finish the job and allowed her to come back.

"I was just trying to fight until the end," said Samsonova, a winner in Berlin four years ago.

"I said, 'okay, until the last ball, I will try to push and try to find my game.'"

She did just that to set up a round of 16 match against third seed Jessica Pegula.

Australian Open champion and seventh seed Madison Keys also suffered an early exit, with Czech Marketa Vondrousova, the 2023 Wimbledon champion, moving into the next round with a 7-5 7-6(6) win.

Vondrousova, who had been out for three months earlier this year with a shoulder injury, will face Diana Shnaider in the round of 16 after the 21-year-old Russian overran Croatia's Donna Vekic 6-2 6-4.

The southpaw powered through the first four games and before Vekic had any time to react, she had wrapped up the first set with her fourth set point.

READ MORE: Philippine wild card stuns Keys, Djokovic sets Masters 1000 record

Shnaider then found a bit more resistance with her opponent earning early break only to be immediately broken back twice as the world number 12 bullied the Croat with punishing groundstrokes to go 5-4 up and seal the win on Vekic's serve.