Serena Williams has advanced to her fifth Australian Open final after beating China's Li Na 7-6 (4), 7-6 (1), her 50th match win at Melbourne Park.

Williams dominated the second-set tiebreaker, clinching the match with an ace, after the Chinese player had saved three match points in the 10th game and one in the 12th.

In the first tiebreaker, Williams picked up four of her last five points on unforced errors by Li and the American clinched the set with a second-service ace.

Williams has a perfect record in Melbourne Park finals, having won titles in 2003, 2005, 2007 and last year.

Justine Henin or China's Zheng Jie will attempt to break that streak _ they played the other semifinal later Thursday to determine who takes on Williams in Saturday night's final.