Olympics Rio 2016: Andy Murray shows mettle to reach semi-finals with win over Steve Johnson

Following an exacting joust with Italian Fabio Fognini in the last 16 on Thursday in which the British number one Murray won six straight games in the deciding set to progress after trailing 3-0, Murray was again pushed to the limit by world number 22 Johnson after two hours and 11 minutes of an utterly engrossing battle in Brazil before completing a 16th straight win.

He last lost to Novak Djokovic in the French Open final in June, but his powers of recovery will be tested to the limit having spent over four hours on court in his past two matches at the Rio tennis centre.

Murray - who downed Roger Federer in straight sets to win gold four years ago in London - will face Kei Nishikori on Saturday for a place in Sunday's final after Japan's fourth seed completed a 7-6 (7-4) 4-6 7-6 (8-6) win over Gael Monfils in another tight contest.

It was only the second time the pair had met, but while Murray had completed a 6-2 6-4 win on another hard court joust in Shanghai last year, this one proved altogether more problematic as Johnson - who enjoyed 31 winners compared to 24 by his world number two opponent - simply refused to slip quietly into the night after being whitewashed in the first set.

With Murray apparently distracted towards the end of the second set, Johnson restored parity, one break in the opening game of the second set enough to give him his first game of the match, and seemed on course for a huge upset when he broke for a 4-3 lead in the deciding set.

But three-times Grand Slam champion Murray refused to panic, and promptly broke back before seeing off a Johnson break point at 4-4 in the third set which appeared to be a virtual match point due to the fearless way the California native was approaching the ball.

There were no further breaks of serve as the match headed for a nerve-jangling breaker, but Murray seized control early on and apart from a running backhand winner from Johnson that defied belief to close to 4-2 behind, Murray picked up the next three points to move one win away from another appearance in the Olympics' gold medal match.

In the top half of the draw, Argentina's Juan Martin Del Potro beat Roberto Agut Bautista of Spain 7-5 7-6 (7-4) to secure a semi-final with Rafael Nadal who came from a set behind against Brazilian Thomaz Bellucci to complete a 2-6 6-4 6-2 succcess.