KEY BISCAYNE, Fla. (AP) -- The grunts were long and loud in the final game, as if Maria Sharapova was pushing a couch across nearby Crandon Beach.
Trying to win the Sony Open must feel that way to Sharapova, a four-time runner-up. She returned to the semifinals Wednesday despite a patchy performance, beating Sara Errani 7-5, 7-5.
Sharapova had 57 unforced errors, including 13 double-faults, and overcame three set points in the second set.
''I made things much more difficult than they should have been,'' she said.
The two sets took 2 1/2 hours, and a flurry of mistakes by both players left spectators groaning. Sharapova had the last laugh, whacking a forehand winner past Errani on match point.
''She really made me work for this match,'' Sharapova said. ''I had to dig deep - so many opportunities, a few ups and downs. I'm definitely happy to get through another one.''
Seeded No. 3, she'll play Thursday against No. 22 Jelena Jankovic, who beat No. 15 Roberta Vinci 6-4, 6-7 (6), 6-3.
The men's quarterfinals featured eight Europeans for the first time, and in the opening match, No. 3 David Ferrer of Spain rallied past unseeded Jurgen Melzer of Austria, 4-6, 6-3, 6-0. Ferrer's opponent Friday will bracket buster Tommy Haas of Germany, who beat No. 11 Gilles Simon of France, 6-3, 6-1.
The 34-year-old Haas became the oldest man to beat a No. 1 player in a completed match in 30 years when he upset three-time champion Novak Djokovic on Tuesday night.
Sharapova faced Errani in a rematch of last year's French Open final, which Sharapova won to complete a career Grand Slam. But she has never won Key Biscayne, losing the final in 2005, '06, '11 and '12.
''I've been so close to winning,'' Sharapova said. ''I would love to win this. I've been coming to this tournament since I was a little kid as a spectator. To be playing here, to be doing so well and getting to that stage, I sure hope I can go further this time.''
Her quarterfinal took place with the stadium half empty despite postcard weather. Attendance is down about 7 percent from last year, and promoters blame the absence of Rafael Nadal and Roger Federer.
Sharapova struggled with both her first and second serves, and in the second set she lost eight consecutive service points. While she and Errani waged a series of long, entertaining baseline rallies, both were also prone to blowing easy shots.
Sharapova's superior firepower proved the difference. Serving at 4-5 in the second set, she erased three set points and held. Two games later she endured one final double-fault, then hit winners on the last two points.
Errani, seeded No. 8, fell to 0-26 against opponents ranked in the top five. She's 0-4 against Sharapova.
''It's nice to get through a match when you don't feel like you're playing your best, because you feel like you have a lot to improve,'' Sharapova said. ''You have no choice. It's a semifinal.
''Would I have loved to play better? Of course. But some days you can't go out on the court and everything goes in and you feel great and you're playing the way you imagined to play. It just doesn't happen.''
Sharapova has won 10 consecutive matches, all in straight sets. She won the Indian Wells championship this month and is bidding to become the third woman to claim that title and Key Biscayne in the same year. Steffi Graf did it in 1994 and 1996, and Kim Clijsters won both in 2005.