Subdued Nadal struggles to prove fit for purpose

World No 3 looks out of sorts despite straight sets victory over compatriot

Rafael Nadal seems to have spent as much time on the physiotherapist's couch as he has on the tennis court in the last three months and the world No 3 was flat on his back again here yesterday. It was an abdominal injury rather than knee trouble this time, though it did not stop him progressing to the fourth round of the US Open. Nadal beat his fellow Spaniard, Nicolas Almagro, 7-5, 6-4, 6-4.

Nadal, who returned recently after a two-month absence with tendinitis in his knees that forced him to miss Wimbledon, called for the trainer in the third set and had treatment for an injury that first troubled him in Cincinnati last month.

He refused to discuss the problem after the match. "I don't want to talk about injuries," he said. "I'm sorry. I'm a little bit tired of talking about injuries. I'm here to try my best every day. I won the match in three sets, so I'm happy about that. I'm going to try my best in the next round. That's all."

Nadal's pleasure at reaching the last 16, in which he will meet the winner of last night's match between Gael Monfils and Jose Acasuso, was understandable, but whether he is in either the physical shape or the form to make much more progress is another matter. He looked vulnerable against Nicolas Kiefer and dropped his serve five times here against an opponent who rarely excels away from his favoured clay courts.

It was a curious match all round, with both men lying on the court in the third set as Almagro also had treatment on his back. There were a remarkable 13 breaks of serve. The pattern was established early on, with Nadal losing the first two games and winning the next three. The Australian Open champion failed to serve out for the set at 5-4, Almagro breaking on a double fault, but recovered to win the next two games.

More breaks of serve and more patchy passages of play followed in the next two sets. Nadal, who went into the tournament seeded to meet Andy Murray in the semi-finals, never looked in any real trouble but fell below the standards he had been setting earlier in the year.

Nadal was not the only seed in the bottom half of the draw in physical difficulties. Juan Martin del Potro called for a trainer to treat a problem in his right arm during his 6-1, 3-6, 6-3, 6-3 victory over Daniel Koellerer, while Gilles Simon retired after the recurrence of a knee injury when two sets to one down against Juan Carlos Ferrero. Del Potro, who still managed to hit 20 aces, now meets Ferrero for the right to play the winner of yesterday's late-night match between Andy Murray and Taylor Dent.

Jo-Wilfried Tsonga, who is the highest-ranked man not to drop a set in the first three rounds, progressed at the expense of his fellow Frenchman, Julien Benneteau, winning 7-6, 6-2, 6-4. The No 7 seed now plays Fernando Gonzalez, who beat Tomas Berdych 7-5, 6-4, 6-4.