Andrea Petkovic overcame an inconsistent serve and unseeded Kiki Bertens to reach the quarterfinals of the French Open with a 1-6, 6-2, 7-5 victory on Monday.

The 28th-seeded German was broken three times in the first set, once in the second and three more times in the third. But she was able to earn seven breaks of her own all in the final two sets to advance to the quarterfinals at Roland Garros for the second time in her career.

“I was really relieved that I picked myself up after I was up 4-2 in the third and I started playing a little passively,” Petkovic said. “I wasn’t going for my shots anymore. I was sort of hoping that she’s going to miss. She’s too good for that.

“After going down 5-4 in the third, I just sort of told myself, ‘OK, listen, you have to play aggressive. You have to go for your shots, and nobody’s going to give you the quarterfinals just because you’re nice, so go gain it.”

Bertens, a Dutchwoman ranked No. 148, had been bidding to become the lowest ranked woman to reach the French Open quarterfinals since the field at the clay-court major was expanded to 128 players in 1983.

After splitting the first two sets, the players exchanged breaks quickly and often in the third. Each of the first five games went to the returning player, with Petkovic finally holding to lead 4-2.

Both players were broken once more, but Petkovic was able to hold in the last game with a forehand winner on match point.

“It was super tough, because I didn’t know her at all. I just stalked her on YouTube yesterday the whole day, and I was already impressed yesterday,” Petkovic said. “I think she’s going to be a force on the WTA when she gets fitter and recovers from her injuries that she’s had.”

Petkovic reached the quarterfinals at Roland Garros in 2011. She reached the same stage at the Australian Open and U.S. Open that year for her best Grand Slam performances.

Fifth-seeded David Ferrer also advanced to the quarterfinals, beating 19th-seeded Kevin Anderson of South Africa 6-3, 6-3, 6-7 (5), 6-1. Ferrer reached the final last year but lost to eight-time champion Rafael Nadal.

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