Monica Puig reached the Olympic Games women's tennis singles final on Friday to stand one victory away from giving Puerto Rico its first ever gold medal.
The 22-year-old 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.
Kerber or Keys in final
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."
Nadal on course for double gold
Meanwhile, Rafa Nadal took another step closer to a double gold medal haul when he quelled the fierce resistance of Brazilian number one Thomaz Bellucci to reach the men's singles semi-finals.
The third seed triumphed 2-6, 6-4, 6-2 to secure a sixth win in six matches against his fellow left-hander who was carried to a shock first set success by the raucous centre court crowd who were in a carnival mood.
Nadal, the 2008 singles champion, goes on to face either Juan Martin del Potro of Argentina or compatriot Roberto Bautista Agut for a place in Sunday's gold medal match.
Victory will allow Nadal to join Serena Williams, Venus Williams and Nicolas Massu as the only players to have won gold in singles and doubles at an Olympics.
Defending Olympic champion Andy Murray also reached the semi-finals after winning a third-set tiebreak to scrape through a testing encounter against American Steve Johnson.
Britain's Murray, the world number two, edged into the last four 6-0 4-6 7-6(2) but was pushed to the limit by the 22nd-ranked Johnson, who came back to win the second set after being brushed aside in the first.
The players traded service breaks and blazing passing shots in the final set, but Murray showed steady nerves to win the tiebreak, closing out the match with a deftly placed overhead smash.
Murray will face the winner of the match between Japan's Kei Nishikori and Gaël Monfils of France.