<p>Serena Williams reached the WTA Finals semis and was crowned year-end world number one without picking up a racquet on Friday when results went her way at the season finale in Singapore.<br /><br /></p>.<p>The four-time champion was in stark danger of crashing out but she earned a reprieve when Simona Halep, her tormentor in a crushing 6-0, 6-2 defeat earlier this week, won a set against Ana Ivanovic.<br /><br />And more stars aligned for the 18-time Grand Slam-winner when world number two Maria Sharapova made an early exit — ending her chances of overtaking the American in the year’s final rankings. Caroline Wozniacki stormed past Petra Kvitova 6-2, 6-3 to set up a semifinal against Williams on Saturday, while Halep will play Agnieszka Radwanska in the last four.<br /><br />Ivanovic departs despite beating Halep 7-6 (9-7), 3-6, 6-3, while Sharapova also leaves after rallying for a 7-5, 6-7 (4-7), 6-2 win over Radwanska.<br /><br />Under complex round-robin calculations, Sharapova needed a straight-sets victory to survive and she came agonisingly close when she passed up three match points in the second set.<br /><br />While Sharapova's season is over, Wozniacki's is still very much in play after a victory over Kvitova that left her as the only player in the tournament to win all the group matches.<br /><br />Super-fit Wozniacki, who is training for next month's New York marathon, again made all the running as she beat Kvitova in 69 minutes. Following her three-hour slugfest against Sharapova and straight-sets win over Radwanska, the resurgent former world number one has hit a patch of form that has re-announced her as a force in women’s tennis.<br /><br />Later Ivanovic fought bitterly for the straight-sets win over Halep that she needed to stay alive, and momentum was with her when she came from behind to win the first set on a tie-breaker.<br /><br />But the former French Open champion missed an open-court volley as she was broken early in the second set, which she lost 6-3. But like Sharapova, she gathered herself for an all-out effort in her final set of the season and she took it 6-3 to seal the win.</p>
<p>Serena Williams reached the WTA Finals semis and was crowned year-end world number one without picking up a racquet on Friday when results went her way at the season finale in Singapore.<br /><br /></p>.<p>The four-time champion was in stark danger of crashing out but she earned a reprieve when Simona Halep, her tormentor in a crushing 6-0, 6-2 defeat earlier this week, won a set against Ana Ivanovic.<br /><br />And more stars aligned for the 18-time Grand Slam-winner when world number two Maria Sharapova made an early exit — ending her chances of overtaking the American in the year’s final rankings. Caroline Wozniacki stormed past Petra Kvitova 6-2, 6-3 to set up a semifinal against Williams on Saturday, while Halep will play Agnieszka Radwanska in the last four.<br /><br />Ivanovic departs despite beating Halep 7-6 (9-7), 3-6, 6-3, while Sharapova also leaves after rallying for a 7-5, 6-7 (4-7), 6-2 win over Radwanska.<br /><br />Under complex round-robin calculations, Sharapova needed a straight-sets victory to survive and she came agonisingly close when she passed up three match points in the second set.<br /><br />While Sharapova's season is over, Wozniacki's is still very much in play after a victory over Kvitova that left her as the only player in the tournament to win all the group matches.<br /><br />Super-fit Wozniacki, who is training for next month's New York marathon, again made all the running as she beat Kvitova in 69 minutes. Following her three-hour slugfest against Sharapova and straight-sets win over Radwanska, the resurgent former world number one has hit a patch of form that has re-announced her as a force in women’s tennis.<br /><br />Later Ivanovic fought bitterly for the straight-sets win over Halep that she needed to stay alive, and momentum was with her when she came from behind to win the first set on a tie-breaker.<br /><br />But the former French Open champion missed an open-court volley as she was broken early in the second set, which she lost 6-3. But like Sharapova, she gathered herself for an all-out effort in her final set of the season and she took it 6-3 to seal the win.</p>