The big four are scheduled to clash in the semi-finals here at Wimbledon and all overcame potentially tricky opponents to advance.

Defending champion Rafael Nadal battled through an injury and past powerful Argentine Juan Martin Del Potro in four sets 7-6 (8-6) 3-6 7-6 (7-4) 6-4.

The Spaniard appeared to be in real trouble towards the end of the first set when the doctor was called on court. An injury time-out was granted before the start of the tie-break to allow for Nadal to have more strapping applied to his left foot, much to the annoyance of his opponent who voiced his disapproval to the umpire.

Once play resumed, Nadal fell behind 0-3 in the tie-break but rallied back into contention, saving a set point along the way before taking the set thanks to a Del Potro double-fault.

Del-Potro was not ready to give up though and powered through Nadal's stern defence to comprehensively take the second set 6-3 and level the match.

From then on the two players were locked close in battle and the third set was also decided by a tie-break which the defending champion took by seven points to four.

The high level of play from both continued in the fourth but Nadal's brilliance shone through at 2-2 when he managed to break the Del Potro serve for the first time in the match to lead 3-2. The Spaniard forged on and closed out the match after three hours and 52 minutes.

Nadal goes on to face American Mardy Fish in the quarter-finals after Fish defeated last year's runner-up Tomas Berdych of the Czech Republic 7-6 6-4 6-4.

Former world number one Roger Federer is also through after he defeated Russia's Mikhail Youzhny 6-7 (7-5) 6-3 6-3 6-3 to set up a quarter-final meeting with France's Jo-Wilfried Tsonga.

Tsonga advanced at the expense of Spanish 7th seed David Ferrer 6-3 6-4 7-6 (7-1).

Novak Djokovic and Andy Murray both advanced in straight sets in their fourth-round ties with Murray seeing off the challenge of Frenchman Richard Gasquet 7-6 (7-3) 6-3 6-2 and Djokovic trouncing Gasquet's compatriot Michael Llodra 6-3 6-3 6-3.

Feliciano Lopez of Spain and Bernard Tomic of Australia were also winners on Wednesday.

Lopez overcame Kubot of Poland in five tough sets 3-6 6-7 (5-7) 7-6 (9-7) 7-5 7-5 and Tomic beat yet another higher-ranked player on his excellent run here at Wimbledon when he defeated Xavier Malisse of Belgium 6-1 7-5 6-4.