Serena Williams clinches year-end No. 1

Serena Williams will finish as year-end No. 1 for the third time in her career. (Andy Lyons/Getty Images)

Serena Williams has clinched the year-end No. 1 ranking for the third time in her career, according to the WTA Tour.

Williams, who turned 32 on Thursday, is 67-4 this year with a career-high nine titles and a record $9.1 million in earnings. She won her first French Open since 2002 and defended her title at the U.S. Open earlier this month. Williams had a 34-match winning streak before losing to Sabine Lisicki in the fourth round of Wimbledon.

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In February, Williams recaptured the No. 1 ranking for the first time since 2010 and became the oldest woman to hold the top spot since the computer rankings were introduced in 1975.