Former world number one Martina Hingis was knocked out in the third round of the German Open on Thursday, losing 6-4, 6-0 to fellow Swiss Patty Schnyder.

Hingis was clearly struggling with a back injury and was broken seven times by Schnyder in a match interrupted several times by rain.

The five-times Grand Slam winner said she had considered retiring from Thursday's match and could skip next week's Italian Open if she failed to regain her fitness.

"Patty was very solid -- and smart because she knows I have that little (injury)," Hingis said at a news conference. "She was patient and it was a good match for her."

The persistent rain meant world number one and top seed Justine Henin was unable to play her third-round tie against unseeded Maria Elena Camerin.

If Henin defeats the Italian she will face Jelena Jankovic. The Serbian fifth seed went through after China's Peng Shuai was forced to retire leading 3-2 in the third set.

Wimbledon champion Amelie Mauresmo, back after a two-month layoff, was up 6-2, 1-1 against unseeded Ukranian Julia Vakulenko when their match was suspended as darkness fell over the Steffi Graf stadium.

The winner of that match will play Dinara Safina in the quarters after the Russian eighth seed overcame Lucie Safarova of the Czech Republic 3-6, 6-3, 6-2.

Defending champion Nadia Petrova brushed aside fellow Muscovite Elena Dementieva 6-3, 6-3.

The seventh seed broke Dementieva four times and will play another Russian, third seed Svetlana Kuznetsova, for a place in the last four.

Kuznetsova had a comfortable 6-3, 6-2 win over unseeded German Martina Mueller, ending hopes of a local success at the claycourt event.

Serbian teenager Ana Ivanovic also went through. The number 12 seed was leading Alona Bondarenko 6-3, 5-0 when the Ukrainian sprained her ankle and retired. Ivanovic will play Schnyder in the quarters.

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