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

It was a disappointing start to the former world No. 1's grass season, with Wimbledon starting in just under two weeks. The 27-year-old has struggled to regain her previous elite form 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.