MELBOURNE, Australia (AP) Roger Federer's 1,000th match was similar to most in his career - no-nonsense, dominating from the start, some incredible shots, and yes, victory.

Four-time champion Federer advanced to his ninth straight Australian Open semifinal with a 6-4, 6-3, 6-2 win Tuesday over Juan Martin del Potro, the man who beat him for the U.S. Open title in 2009.

It's a lot of matches and a lot tennis,'' Federer said.Either I have been around for a long time or I'm extremely fit. You decide which way you want to describe it. But I'm happy.''

In the semifinals, Federer will play the winner of the Tuesday's other quarterfinal between second-seeded Rafael Nadal and Tomas Berdych, a rematch of the 2010 Wimbledon final won by Nadal.

Defending women's champion Kim Clijsters, still dealing with a left ankle injury, advanced to a semifinal against third-seeded Victoria Azarenka by beating No. 1 Caroline Wozniacki 6-3, 7-6 (4) Tuesday. Clijsters' victory ensured that Wozniacki would lose the top ranking she has held for most of the last 15 months.

Azarenka beat Agnieszka Radwanska 6-7 (0), 6-0, 6-2. Azarenka is one of three women who could finish at No. 1 in Melbourne - Maria Sharapova and Petra Kvitova are the others

On Wednesday, Sharapova plays Ekaterina Makarova, who beat five-time champion Serena Williams in the fourth round, and No. 2 Kvitova takes on unseeded Sara Errani of Italy.

Federer's career, including a record 16 Grand Slam singles victories, can be enhanced even more if he wins the title this year at Melbourne Park. With a 232-34 record in Grand Slam singles matches, he'd overtake Jimmy Connors' mark of 233 wins with victories in the semifinals and Sunday's final.

The quarterfinals on the other side of the men's draw are on Wednesday - Andy Murray plays Kei Nishikori of Japan and top-seeded Novak Djokovic takes on David Ferrer. They'll have a tough time matching the quality of the Federer-Del Potro encounter.

Del Potro, who has recovered from the right wrist injury that sidelined him for most of 2010, played well in flashes. But Federer was at another level, hitting lobs, drop shots, cross-court winners and generally negating Del Potro's big forehand.

We have played some big matches against each other, so just knowing how well he's been playing as of late, I was just hoping that I would get off a good start,'' Federer said.I was able to mix it up well and control the ball, and right away sort of felt confident, which then sort of helped me to use all aspects of my game.''

The end of the match came in a most fitting way, one of Federer's backhand winners.

Before that, Federer saved his fourth break point at 5-3 in the second set after a long rally. He let out a loud yell, unusual for a player not prone to big celebrations.

That's why I didn't celebrate when I won the set, just to make it up,'' Federer said, smiling.I really knew how important that game was for me.''

Clijsters has needed continual treatment on her ankle since Sunday, when she injured it and had to save four match points in her fourth-round win over Li Na, a rematch of the 2011 final.

Yeah, instead of really focusing on the match you're focusing on trying to get the ankle as good as possible,'' Clijsters said of her preparation.Laying on the couch, every 20 minutes ice, 20 minutes off, 20 minutes ice, 20 minutes off. Leg elevated. Lymphatic drainage, all that stuff.''

Wozniacki needed to reach the semifinals to retain the top ranking.

I will get it back eventually, so I'm not worried,'' she said. Criticstalk to me like I'm finishing my career and I only have one year left and time is running out. The fact is I still have quite a few good years in front of me.''

Azarenka struggled through a match that contained 15 service breaks, including eight in the first set. After being comprehensively outplayed in the opening tiebreaker, Azarenka won seven straight games to gain control.

The 22-year-old Azarenka, who makes a distinctive hooting sound as she hits the ball, extended her winning streak this season to 10 matches, including a title at Sydney, where she beat Radwanska in the semifinals. She served six double-faults and had 38 unforced errors.