Top seed Roger Federer of Switzerland fought through the longest three-set singles match in the Open era on Friday, when he beat Argentina's Juan Martin del Potro 3-6, 7-6(5), 19-17, to reach the Olympic final.
Federer, who returned to Wimbledon's centre court just a month after taking the title there, won after a marathon third set which lasted 163 minutes.
Federer, who has 17 Grand Slam singles titles, has never won an Olympic medal in the singles event.
Federer was on the brink of a shock defeat on Centre Court after dropping the first set, but the world No.1 finally subdued del Potro after a marathon four hours and 26 minutes.
The match, 23 minutes longer than Rafael Nadal and Novak Djokovic's Madrid semifinal in 2009, comes after Jo-Wilfried Tsonga took 66 games to beat Milos Raonic in the second round — the most ever seen in an Olympic three-setter.
“I don't think I've ever played as long a set in a best of three match,” Federer said. “The whole match was nearly four-and-a-half hours, so it was very physical at the end and so mental.s
“I was calm but serving to stay in the match so many times is hard and it takes its toll.
“May a bit of fitness was the difference. I liked my attitude today, so I am very happy. I got my first (singles) medal for Switzerland."
Serena meets Sharapova
Meanwhile in the women’s section, Serena Williams set up a final showdown with old rival Maria Sharapova after routing world No.1 Victoria Azarenka 6-1, 6-2 in the semifinals.
Serena has been in dominant form at the Games as she chases a first singles gold medal and Belarus's Azarenka was no match for the imperious American fourth seed, who cruised to victory in just 63 minutes on Wimbledon's Centre Court.
Third seed Maria Sharapova, who is competing at her first Olympics, beat her compatriot Maria Kirilenko 6-2, 6-3.
“It's incredible, not only to be part of this event and be an Olympian, but to put yourself in with an opportunity to go for gold. It's a really nice feeling,” said Sharapova.
The results (Semifinals):
Men: Singles: Roger Federer (Sui) bt Juan Martin del Potro (Arg) 3-6, 7-6(5), 19-17. Doubles: Bob Bryan & Mike Bryan (USA) bt Julien Benneteau & Richard Gasquet (Fra) 6-4, 6-4; Jo-Wilfried Tsonga & Michael Llodra (Fra) bt Feliciano Lopez & David Ferrer (Esp) 6-3, 4-6, 18-16.
Women: Singles: Maria Sharapova (Rus) bt Maria Kirilenko (Rus) 6-2, 6-3; Serena Williams (USA) bt Victoria Azarenka (Blr) 6-1, 6-2. Doubles: Andrea Hlavackova & Lucie Hradecka (Cze) bt 1-Liezel Huber & Lisa Raymond (U.S.A.) 6-1, 7-6(2); Sabine Lisicki & Christopher Kas (Ger) bt Roberta Vinci & Daniele Bracciali (Ita) 4-6, 7-6(2), 1-0(7).