Rio de Janeiro: Andy Murray battled through a second successive three-setter to reach the Olympic Games semi-finals Friday while Monica Puig was one win away from delivering Puerto Rico a first ever gold medal.
Defending champion Murray clinched a 6-0, 4-6, 7-6 (7/2) win over Steve Johnson of the United States and goes on to face either Japanese fourth seed Kei Nishikori or France's Gael Monfils for a place in the gold medal match.
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.
"I expected a tough match. The court is very lively, there's a lot of wind, so it makes it hard to play," said world number two Murray.
"If I win tomorrow I am guaranteed a medal. If I lose, I have to come back and play for a bronze. As tennis players we are not used to that."
Puig, 22, reached the women's singles final and is already guaranteed at least a silver -- only her country's ninth medal at a Games.
She reached Saturday's final by beating two-time Wimbledon champion Petra Kvitova 6-4, 1-6, 6-3 in a rollercoaster match which featured 10 breaks of serve.
Puig, the world number 34, will face either German second seed, and Australian Open champion, Angelique Kerber or American seventh seed Madison Keys for the title.
"It would be unbelievable to win the gold and it would be the biggest honour in the world," said world number 34 Puig.
"But the Olympics isn't about me, it's about Puerto Rico and I know how bad they want this.
"The island is full of such bad news all the time, so every time there's a Games and somebody from the Island wins a medal everything stops and I know how happy people get. So this one is not for me."
Kvitova faces the prospect of having to return Saturday and battle for a bronze medal in the third-place play-off.
"I'm very disappointed I have to say. I think this feeling, I haven't really had for a very long time," said the Czech 11th seed.
"It was a match I could've won but for sure I didn't take my chances."
Murray is also well-placed for a golden double this weekend.
As well as being in the singles semi-finals, the 29-year-old returns to partner Heather Watson in the mixed doubles last-eight.
The British pair face Sania Mirza and Rohan Bopanna of India.
Venus Williams, chasing a fifth career Olympics gold, teams with Ranjeev Ram for a mixed quarter-final against Italy's Roberta Vinci and Fabio Fognini.