PARIS- Czech left-hander Petra Kvitova reached the French Open quarter-finals for the first time in eight years as she overpowered China's Zhang Shuai 6-2 6-4 on Monday.

On yet another chilly day in the French capital, seventh seed Kvitova's superior firepower proved decisive as she posted her fourth successive straight-sets victory.

With so many big names already out, Kvitova will sense a golden title opportunity as she heads into a quarter-final against either Germany's Laura Siegemund or Spain's Paula Badosa, neither of whom are seeded.

The 30-year-old Czech, who reached the semi-finals in 2012, made her intentions clear from the start as she seized on anything short to dominate from the baseline, moving 4-0 ahead in 15 minutes on Court Philippe Chatrier.

Zhang, in the fourth round of a Slam for only the third time in 33 attempts having also not dropped a set so far, finally began to dig her heels in as Kvitova's error-count increased but she was unable to turn the tide.

Kvitova had to wait around in the cold as Shuai took a medical timeout at the end of the first set, but she turned up the heat to get an early break in the second set.

She broke again to lead 5-2 but some wild errors allowed Zhang to win two straight games and create some tension.

Kvitova regained her focus though to seal victory with a love service hold.

(Reporting by Martyn Herman; editing by Ken Ferris) ((martyn.herman@thomsonreuters.com; +442075427933; Reuters Messaging: martyn.herman@thomsonreuters.com@reuters.net))