Last updated on .From the section Olympics

Britain's Andy Murray remains on course to win back-to-back Olympic tennis gold medals after beating Japanese fourth seed Kei Nishikori in the semi-finals.

The Scot won 6-1 6-4 and will play Juan Martin del Potro in Sunday's gold-medal match (19:00 BST) after the Argentine beat Spain's Rafael Nadal.

Del Potro, ranked 141st in the world, won 5-7 6-4 7-6 (7-5).

World number two Murray, 29, is attempting to become the first player to win two Olympic singles titles.

He won his second Wimbledon - and third Grand Slam - last month.

"It's obviously not an easy thing to do, that's why it's never been done before," said Murray about the prospect of another gold medal.

"I'm going to give my best effort and I'm happy I'm guaranteed the medal, but the goal is obviously the gold."

After coming through two gruelling matches, Murray dominated against Nishikori, breaking his opponent twice to win the first set in 30 minutes.

The Briton was unhappy to get a code violation in the second set as he argued with umpire Carlos Ramos, but he remained in control of the action on court.

Nishikori appeared to wilt in the Rio heat as he dropped serve midway through the second set with a dreadful game.

Murray served his way to an unexpectedly simple victory, winning arguably the point of the tournament, a 23-shot rally, to set up a third match point.

Del Potro through after epic encounter

While the first semi-final was a pretty straightforward affair, the second was anything but in front of a packed and raucous stadium.

Nadal, who won gold in the men's doubles with Marc Lopez on Friday, took the first set before Del Potro levelled.

Both players played superbly in the decider, with Nadal breaking back at 5-4 down with some wonderful shots - but it was eventually in vain as the Argentine won the decider 7-5 in the tie-break.

Del Potro, 27, who collapsed to the ground in celebration and kissed the Olympic emblem, won bronze at London 2012.

"It means a lot to me. It's very big, maybe even more special than when I won the US Open," said Del Potro, who was mobbed by Argentine fans at the end.

"I didn't expect to get to the final, I didn't expect to beat Djokovic. I am living a dream and the crowd make me cry after every match."