Williams to finish as year-end No. 1

Singapore (SportsNetwork.com) - Serena Williams didn't even lift a racket Friday, but still clinched the year-end No. 1 ranking on the WTA Tour.

The American star was ensured of finishing in the top spot after Maria Sharapova failed to qualify for the semifinals at the season-ending WTA Finals.

Sharapova was the only player who could have surpassed Williams, but needed to win the tournament and have Williams not reach the final. The Russian star won her match Friday against Agnieszka Radwanska, but needed to win it in straight sets and the Pole pulled out the second set.

If Sharapova had won in straight sets -- she was up 7-5, 5-1 against Radwanska and failed to close it out early -- Caroline Wozniacki's win over Petra Kvitova would have kept the Russian alive in the tournament, and in the race for No. 1.

Williams, who nearly was eliminated from the tournament herself on Friday, will play in the semifinals on Saturday against Wozniacki. If Ana Ivanovic had beaten Simona Halep in straight sets on Friday, Williams would have been denied a chance at her third straight WTA Finals crown. Ivanovic, however, needed three sets to beat Halep.

The year-end top ranking is the fourth for Williams, who also accomplished the feat in 2002, 2009 and 2013.

Only four others have been No. 1 as many times. Steffi Graf was an eight-time year-end No. 1, while Martina Navratilova did it seven times, Chris Evert five and Lindsay Davenport four.