RIO DE JANEIRO (AFP) - Defending champion Andy Murray battled through a second successive three-setter to reach the Olympic Games semi-finals Friday (Aug 12) with a 6-0, 4-6, 7-6 (7/2) win over Steve Johnson of the United States.

Murray had been 0-3 down in the final set to Fabio Fognini in the third round 24 hours earlier and he was a break down at 3-4 in the decider to the 12th seeded Johnson on Friday before his big-hitting game saw him through.

Murray finished with 31 winners but also 36 unforced errors.

He will face either Japanese fourth seed Kei Nishikori or France's Gael Monfils for a place in the gold medal match.

Friday's other quarter-finals see 2008 champion Rafael Nadal taking on Thomaz Bellucci, the Brazilian number one.

The winner of that tie will meet either Juan Martin del Potro, the conqueror of Novak Djokovic, or Roberto Bautista Agut for a place in Sunday's final.