Melbourne, Jan 28 - Serena Williams fought off the Chinese challenge from 16th seed Li Na, making her way into her fifth final at the Australian Open Thursday 7-6 (7-4), 7-6 (7-1) despite making a hash of four match points.

The US defending champion is set to face either Justine Henin or China's other hope, Zheng Jie, in Saturday's final for her 12th Grand Slam title.

Williams had to fire up to overcome shotmaker Li, who made history by joining her compatriot in the final four - China's finest performance at a major.

Williams screeched as she finally ended her agony with a 12th ace in the tight contest. Should she win the trophy at Melbourne Park for a fifth time, she would tie the women's record of a dozen major singles titles held by tennis pioneer Billie Jean King.

"I had too many match points and I blew them," said Williams, hoping to earn her first Melbourne trophy in an even-numbered year after titles in 2003, 2005, 2007 and 2009.

"I knew I had to close it out on my serve. She never gives up, she's an amazing fighter."

Li, who will become China's first player ranked in the top 10, secured her place by upsetting Venus Williams a day earlier.

"I talked to Venus, she told me how to play her and what do to," Serena said. "That always helps."

Williams was forced into a second-set tiebreaker after failing on four match-winners. The US player was able to convert only one of nine break point chances while dropping her serve once.

Williams struck 33 winners while Li had 21 along with 38 unforced errors.

Thursday's win was Williams's second Australian victory over Li, after she beat the Chinese in the first round of the 2006 tournament, dispatching her in three sets.  (IANS)