Sharapova needs more than 3 hours to win

STUTTGART, Germany — Top-seeded Maria Sharapova needed three sets and more than three hours Thursday in her clay-court debut of the year to overcome Lucie Safarova of the Czech Republic for a place in the quarterfinals of the Porsche Grand Prix.

Sharapova, the defending champion, won 6-4, 6-7 (3), 6-3 in a match that lasted 3:09 hours.

The Russian saved two set points in the second set before surrendering the tiebreaker, in which she had one of her eight double-faults. She also had eight aces.

Sharapova, who used this indoor clay tournament last year to prepare for her French Open victory, broke serve for a 4-2 lead but needed five match points to close out the encounter. The match ended when she hit a net cord that dropped into Safarova's half. Safarova reached it but could only send it back long and wide.

"I've had a few three hour games in my career, so I knew I just had to keep fighting until the end," Sharapova said. "That's when it's the time to get the game-plan going and calm down a little bit."

"Clay is one of her favorite surfaces and I knew this was going to be a tough game, so I am glad to get through. The first match of the clay-court season is always tough, it's nothing like practicing," she said.

Sharapova's quarterfinal opponent will be Ana Ivanovic of Serbia, who beat eight-seeded Russian Nadia Petrova 6-4, 6-3.

Seeded players Li Na, Angelique Kerber and Petra Kvitova advanced to the quarterfinals in different fashion.

The second-seeded Li swept past qualifier Mirjana Lucic-Baroni 6-1, 6-2, and the third-seeded Kerber defeated Anastasia Pavlyuchenkova 6-0, 6-4. The fifth-seeded Kvitova rallied past 2011 champion Julia Goerges 2-6, 7-6 (4), 6-2. Kvitova is the 2011 Wimbledon champion and looking for her second title of the year.

One day after upsetting Caroline Wozniacki, Carla Suarez Navarro lost 7-5, 6-4 to Yaroslava Shvedova.

Kerber will play Shvedeva in the quarterfinals, while Li faces Kvitova.

Sabine Lisicki of Germany beat Jelena Jankovic of Serbia 7-6 (3), 7-5 in a match that could have gone the other way too.

Lisicki needed seven set points to close the first set and used her third match point to finish it, after wasting one of them with a double-fault.