The world number one was in dazzling form at the start of the quarter-final but at a set and 4-2 up his serve deserted him and a series of wayward groundstrokes let the Spanish 12th seed back in.

Ferrer levelled and Federer, who had never lost so much as a set in six previous meetings with Ferrer, only just scraped home.

Federer will continue his preparation for the French Open [ Images ], the only grand slam he has never won, against another Spaniard after Carlos Moya [ Images ] pulled off a great 7-6 4-6 7-5 win over the fast rising Serb Novak Djokovic [ Images ], seeded fourth.

Djokovic, aged 19 and with three titles already this season, lost the tiebreak at the end of an untidy first set 7-4 but hit back strongly in the second.

The 30-year-old Moya, who won at Roland Garros [ Images ] back in 1998, grabbed a break at the start of the third and calmly withstood everything Djokovic could throw at him.

SCOOPED FOREHAND

Moya missed one match point in losing his serve at 5-3 but, crucially, he held his next service game and forced three match points in the next, taking the third of them as Djokovic missed an attempted backhand pass.

Moya will feel he has a real shot at upsetting Federer, who needed a big slice of luck in the final set against Ferrer.

Serving at 3-3 and 30-30, the Swiss saw a scooped forehand hit the top of the net and dribble over. It brought a relieved smile from Federer, while Ferrer threw his racket down in frustration on the red clay.

Federer duly held and took a decisive 5-3 lead when he converted a fifth break point in Ferrer's next service game.

"I was lucky there on the net cord," Federer said at a news conference. "That was huge.

"It was a pity that I didn't close out then in the first set, and leave feeling great. But I'm happy with the way I played."

The favourite Rafael Nadal [ Images ] will look to extend his claycourt winning streak to 80 matches when he takes on fifth seed Fernando Gonzalez [ Images ] of Chile. The reward for the winner of that match will be a semi-final against Nicolas Almagro or 16th seed Lleyton Hewitt [ Images ].