Melbourne, Australia ? Trailing 5-1 in the final set of an Australian Open semifinal against Kim Clijsters, Serena Williams didn’t look like the most dominant player in women’s tennis.

Then, suddenly, the zip came back. Williams saved two match points and surged to a 4-6, 6-3, 7-5 victory Thursday, leaving her one victory away from a “Serena Slam.”

“I really didn’t think I’d win it,” said Williams, bothered by blisters on her feet. “I kept fighting.”

Older sister Venus Williams beat 2001 Wimbledon runner-up Justine Henin-Hardenne 6-3, 6-3 in the other semifinal.

Tonight’s final will mark the first time in more than 100 years of Grand Slam history that two women have met in four straight major finals.

“We love to play each other,” said Serena, who beat Venus in last year’s championship matches at the French Open, Wimbledon and U.S. Open.

On the men’s side, Andre Agassi beat Wayne Ferreira 6-2, 6-2, 6-3 to reach the final. Agassi will play in his 14th Grand Slam final Sunday, against Andy Roddick or Rainer Schuettler.