Germany's Kerber had to draw on all her big match experience to hold off the challenge of the rising star of the women's game, 21-year-old Japanese player Naomi Osaka, and win 6-4, 5-7, 6-4 in Singapore on Wednesday.

After losing her opener to Kiki Bertens of the Netherlands, the 29-year-old knew that failure to put away crowd favorite Osaka would likely end her chances of being the first German woman to win the season-ender featuring the top eight players since Steffi Graf in 1996.

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“It was two or three points that decided the match, I think it was a really good match," Kerber told British broadcaster BT Sport.

"There are a lot of moments, you have to be able to get through it, taking on the challenge. It is still a long way to the semifinal but it is good that I have a win under my belt. 

The momentum swung wildly in a heavy-hitting battle, with Kerber breaking to love in the first game only for Osaka to repeat the trick in the next game. With both players serving poorly, Kerber's next break eventually proved decisive.

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The 30-year-old German, ranked number 2 in the world, looked to complete the match on serve at 5-4 in the second. 

However, Osaka fought back to earn two break points and levelled the match at 5-5 with a brilliant forehand winner. The 21-year-old then rallied to break again and retain some hope of a comeback win in a deciding set. 

But the older player ground her opponent down and the pressure told in the sixth game of the decider when Osaka fell a break behind. Kerber made no mistakes in her second chance to serve for the match.

Kerber's final group stage game is against Sloane Stephens on Friday and a win would almost certainly guarantee her a spot in the last four.

mp/mds (DPA, AFP)