Russia’s Maria Sharapova let slip three match points as she crashed out of the WTA Finals in Singapore and lost her chance on Friday to become the year-end world No.1.

The Russian, needing a straight-sets win to stay alive, won the first set 7-5 but she passed up the match points in the second before Agnieszka Radwanska won a tense tiebreaker 7-4.

Although the third set was yet to unfold, it brought an end to a disappointing campaign for the world No.2 who lost her first two group matches against Caroline Wozniacki and Petra Kvitova.

The 2004 champion also cannot overtake Serena Williams and end the season as No.1 in a boost to the 18-time grand slam-winner whose campaign is also hanging by a thread.

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

Meanwhile, 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.