Fernando Gonzalez has opted to ingratiate himself with quarter-final opponent Roger Federer in the hope it can bring him victory when they clash at the French Open tomorrow.

Gonzalez defeated the world No1 in their last meeting at the Tennis Masters Cup in Shanghai and a hard-fought victory over Robby Ginepri, featuring his trademark howitzer forehand, proved he is a serious threat to Federer progressing further in the only Grand Slam he hasn't won.

Asked to give his verdict on Federer, the Chilean said: "I think what Roger has done is exceptional, it is outstanding. Not many players could have done that."

The 24th seed has a 16-0 winning record on clay in 2008, although he withdrew in Rome because of a hamstring injury. That statistic has been noted by Federer, who had to endure yet more rain interruptions before celebrating a 6-4, 7-5, 7-5 win over Frenchman Julian Benneteau on Centre Court.

Federer does not have the same aura on clay that he creates on grass and hard courts and, with his serve misfiring slightly, he was pushed around the court by the local hero. He said: "Gonzalez doesn't blow you away from the first shot and he is a very streaky player. He can go on a great roll at times, but you have to go against it.

"It is important to serve well, and try to put him on the back foot. You have to play aggressive and it's an interesting match because last time we played I lost."

Unseeded Gael Monfils, of France, reached the last eight by defeating 28th seed Ivan Ljubcic 7-6, 4-6, 6-3, 6-2 and will play fourth seed David Ferrer, who beat Radek Stepanek 4-6, 6-2, 1-6, 6-3, 6-3.