PARIS (Reuters) - Roger Federer withstood two sets of Argentine fireworks before dousing Juan Martin del Potro's challenge with a 3-6 6-7 6-2 6-0 6-3 win on Tuesday to reach the semi-finals of the French Open.
The Swiss third seed's chances of winning a second title here appeared to be sinking fast as he drowned under a hail of winners flying off Del Potro's racket in the opening two sets.
But the 2009 champion stayed calm to break for a 2-0 lead in the third set and from then on Del Potro's dodgy left knee and mindset started to let him down.
The ninth seed won only eight points during a forgettable fourth set and his misery was compounded when he bowed out after a forehand clipped the net and bounced out to hand Federer victory.
Federer, looking for a record 17th grand slam crown, next faces Novak Djokovic or Jo-Wilfried Tsonga for a place in Sunday's final.
(Editing by Pritha Sarkar)