MELBOURNE, Australia (AP) – Maria Sharapova advanced to the Australian Open semifinals with a 7-6 (5), 7-5 win Wednesday over Anna Chakvetadze, another 19-year-old Russian.

The top-seeded Sharapova, assured of gaining the No. 1 ranking next month, had trouble on her serve, serving double-faults on break point three times. But she had the only point on serve in the tiebreaker, where the last eight points finished on unforced errors.

The U.S. Open champion was broken when serving for the match at 5-3 and wasted a match point with a backhand error in the next game.

Sharapova got two more match points in the 12th game and finished it off in 2 hours, 14 minutes when Chakvetadze netted a forehand.

“It was very difficult, I didn’t feel like we had a lot of easy rallies,” Sharapova said. “I felt I had to work on every point.”

Sharapova was very inconsistent, smacking clean winners to take one game, then committing glaring mistakes to lose the next. She finished with 32 winners but six double faults and 41 unforced errors and won only three more points than her opponent.

Sharapova, who looks toward her father, Yuri, after almost every point, got a warning for getting coaching from him as she served at 0-30 with the score tied at 2-2 in the second set. She then ran off four straight points to take the game.

“I was a little up and down, a bit scratchy,” Sharapova said. “I am glad I got through, but next time will even be tougher.”

Sharapova is into the semifinals at Melbourne Park for the third straight year and is among the last four at a major for the eighth time. She is the defending U.S. Open champion and also won Wimbledon in 2004.

Chakvetadze, who had won 20 of her previous 21 matches, had never been beyond the fourth round of a major.

No. 4 Kim Clijsters and three-time champion Martina Hingis were to meet in a quarterfinal here for the second consecutive year.

Clijsters won at that stage last year, ending Hingis’ remarkable run after coming to Melbourne Park with a ranking of 341 following three years in retirement.

In men’s quarterfinals later Wednesday, second-seeded Rafael Nadal faced No. 10 Fernando Gonzalez of Chile and Tommy Haas was against No. 3 Nikolay Davydenko.

On the other side of the draw, Andy Roddick was ruthless, treating his close friend like little more than warmup fodder for his semifinal showdown with Roger Federer.

The 2003 U.S. Open champion flattened Mardy Fish without blinking Tuesday, making only four unforced errors in a 6-2, 6-2, 6-2 quarterfinal win.

“I played pretty flawless, I thought,” Roddick said. “I feel good going into the semis.”

Federer, who lost to Roddick in the final of an exhibition tournament 10 days ago but has a 12-1 record in official ATP matches, dropped his serve four times in a 6-3, 7-6 (2), 7-5 win over No. 7 Tommy Robredo.

“The break of serves, they’re due to the wind I assume,” Federer said. “I had to kind of change my game around a little bit. I think my attacking style really worked out well – I’m really happy to have come through.”

Federer has been ranked No. 1 since February 2004 and next month he’ll break Jimmy Connors’ record of 160 consecutive weeks atop the rankings.

Rod` dick and eight-time Grand Slam winner Connors teamed up as student and coach last July to try and challenge Federer’s domination.

And that has coincided with Roddick returning to the top 10 and becoming a contender again to take a major from Federer.

“For the past probably five or six months, the gap has either been closing a little bit or just he hasn’t been extending it,” Roddick said. “That’s a good thing.

“I feel like I’m in good form. I’d love to see where I match up.”

Serena Williams continued her improbable run for an eighth Grand Slam title, fending off 10 break points and coming within two points of defeat before beating Shahar Peer 3-6, 6-2, 8-6.

That put her into a semifinal against 17-year-old Nicole Vaidisova.

“I am the ultimate competitor,” said Williams, who missed most of last season with recurring knee trouble. “I don’t think anyone thought I would get this far, except for me and my mom.”