Maria Sharapova Out of WTA Finals, Serena Williams Year-End Number One

Maria Sharapova finally got a win at the WTA Finals Friday but it wasn't enough to stop her crashing out of the tournament and blowing her opportunity to be crowned year-end world number one.

The Russian star needed to beat Agnieszka Radwanska in straight sets to stay alive but after winning the first set, she agonisingly lost three match points and a tie-breaker in the second.

Second-ranked Sharapova rallied to win the match 7-5, 6-7 (4/7), 6-2 but the 2004 champion exits the end-of-season tournament in Singapore after her two earlier round robin losses.

"It's so great to get a win in Singapore. I really wanted it today, it was so tough in that second set. We've always had such tough matches against Radwanska and today was no different," she said.

Sharapova is also now unable overtake Serena Williams and become year-end world number one for the first time, meaning the 18-time Grand Slam-winner earns the honour for a fourth occasion.

Sharapova's elimination brought an end to a disappointing campaign for the Russian, who lost her earlier matches against Caroline Wozniacki of Denmark and Petra Kvitova of the Czech Republic.

Sharapova had a 10-2 head-to-head record against Radwanska going into Friday's match and won their last three meetings, but the world number six was unfazed.

Neither player held serve in the first four games but Sharapova eventually edged ahead and took the set after some furious rallies.

In the second, she had the crucial victory on her racquet but passed up two match points at 5-1 and another at 5-3 before Radwanska forced the tie-breaker and snatched it 7/4.

But the Pole looked a spent force in the third set, enabling Sharapova to save face with her only match win in Asia's first staging of the women's season finale.

Radwanska is also relying on the result of Wozniacki's final round robin match with Kvitova if she is to make the semi-finals of the eight-player season finale.

And Williams, shattered 6-0, 6-2 by Simona Halep in her second group match, needs the Romanian to win at least one set against Serbia's Ana Ivanovic later Friday to reach the semi-finals.