MELBOURNE, Australia -- Like Chris Evert, Martina Navratilova, Jennifer Capriati and Lindsay Davenport before them, Venus and Serena Williams did their part Monday to ensure a 34-year-record at the Australian Open remained intact.
The Williams sisters won their fourth-round matches, extending a mark in which an American woman has been in the quarterfinals every year since 1977.
Navratilova, born in Czechoslovakia but who became an American citizen in 1981 -- the same year she won her first Australian title -- won here three times. Evert and Capriati captured it twice each and Davenport and Barbara Jordan once.
Monica Seles won the Australian Open four times, but only once as an American citizen -- in 1996 -- after she changed her citizenship officially from Yugoslavian.
Serena has most recently had four wins at Melbourne Park, while Venus lost to Serena in the 2003 final.
Serena broke Stosur in the opening game of the second set Monday. The American faced two break points in her next service game, but fought back to deuce with an ace and a service winner, then served another ace on game point.
Stosur, who beat Serena the last time the pair met in California last year, set up break point in the seventh game with a double fault, then Serena hit a forehand winner to go up 5-2. Serena then held serve in the next game to take the match.
"It's important when you're playing a local girl to not let the crowd get too involved or else they'll kill you," Serena said.
Serena could add to her Grand Slam total, and Venus could win the Australian Open for the first time, but they can't meet in the final. They're in the same half of the draw and will meet in the semifinals if they win their next matches.
"I think it's challenging because we're both so good," Venus said of the Williams family matchups. "We both want to win. It's just difficult I think for us to play against each other because I think we have so much respect for each other's game."
Venus, who has won seven singles majors, struggled to hold serve in the first set against Schiavone but was in command by the end, when she won the last six games after the 29-year-old Italian broke her to open the third set.
Williams advanced to the Melbourne Park quarterfinals for the seventh time to set up a meeting with Li Na, who helped make Chinese history. For the first time at a major, there's two Chinese players in the quarterfinals.
"Nothing better," Li said, smiling, "Yeah, I mean good for us."