PARIS — Serbia’s Novak Djokovic and Spain’s Carlos Alcaraz stayed on collision course for a golden showdown at the Paris Olympics as they surged through to the quarterfinals on Wednesday.

But Rafa Nadal’s hopes of writing one last golden chapter in his Roland Garros love story ended in disappointment as he and Mr. Alcaraz lost in the quarterfinals of the doubles.

Mr. Djokovic, also in the last-chance saloon as far as his Olympic title hopes go, beat Germany’s Dominic Koepfer 7-5 6-3 to reach the last eight at the Games for a record fourth time where he meets Greek Stefanos Tsitsipas.

The 21-year-old Mr. Alcaraz, seeded second, followed suit with a 6-4 6-2 victory over Russian Roman Safiullin to line up a quarterfinal with American Tommy Paul.

Women’s singles top seed Iga Swiatek became the first player from Poland to reach an Olympic semifinal as Danielle Collins retired trailing 4-1 in the third set of their scrap.

Anna Karolina Schmiedlova stunned Wimbledon champion Barbora Krejcikova of the Czech Republic 6-4 6-2 to become the first Slovak since Miloslav Mecir in 1988 to reach the Olympic singles semifinals and China’s Zheng Qinwen ended the stellar career of Germany’s Angelique Kerber to emulate Li Na who reached the semifinals of singles at the Beijing Games in 2008.

Ms. Kerber, who will retire after the Games, clung on grimly in stifling heat but Zheng eventually won 6-7(4) 6-4 7-6(6) to set up a semifinal with Ms. Swiatek.

Ms. Swiatek trounced Ms. Collins 6-1 in the first set, lost the second 6-2 and was hit painfully by a Collins shot in the decider before moving 4-1 ahead, at which point Collins pulled out.

Unseeded Croatian Donna Vekic concluded a marathon day as she served an ace on her fifth match point, having also saved one, to beat Ukraine’s Marta Kostyuk at gone midnight.

Ms. Vekic, who lost the longest ever Wimbledon women’s semifinal to Jasmine Paolini this month, needed two hours 59 minutes to win 6-4 2-6 7-6(8) and will play Schmiedlova — meaning at least one unseeded player will win a women’s singles medal.

For all his 24 Grand Slam titles and countless accolades, the Olympics has never been especially kind to the 37-year-old Mr. Djokovic and a bronze medal remains his only souvenir. — Reuters