Jo-Wilfried Tsonga has admitted that he is "feeling good" after beating Tomas Berdych in the French Open fourth round.

The home favourite defeated the world number four in four sets on Sunday to book his place in the quarter-finals at Roland Garros.

Following a disappointing start to the year that has seen him slip down to 15th place in the rankings, Tsonga insists that he is still capable of beating the world's top players.

"I'm feeling good," he is quoted as saying by the ATP's official website. "I'm playing good tennis. I'm solid. When I play my best tennis, I know I'm able to beat many guys. So even if the last couple of months was tough, I always believed in myself. I continue to work hard and try to be really consistent in my head."

Tsonga will meet fifth seed Kei Nishikori in the last eight of the tournament.