Argentina's Juan Martin del Potro ended Rafael Nadal's hopes of a second Olympic singles title when he edged a gruelling semi-final Saturday, 5-7, 6-4, 7-6, (7/5) to face defending champion Andy Murray for the gold medal.

The world number 141 Del Potro, whose career was almost ended by a series of wrist surgeries, triumphed after three hours and eight minutes of epic action.

Second seed Murray reached his second successive Olympic final with a ruthless 6-1, 6-4 demolition of Japan's Kei Nishikori.

Nadal, the 2008 singles champion, had won the men's doubles on Friday with Marc Lopez but playing his 10th match of the tournament finally told on him.

Murray can become the first player to defend an Olympic singles title on Sunday but he must get past a resurgent Del Potro, who also shocked world number one Novak Djokovic in the first round.