Novak Djokovic and Carlos Alcaraz overcame crushing humidity on Wednesday to stay on course for an Olympic final showdown as Rafael Nadal played possibly his final match at Roland Garros. Djokovic, seeking a first Olympic title to add to his record-breaking collection, defeated German left-hander Dominik Koepfer 7-5, 6-3, becoming the first man to reach four singles quarter-finals at the Games. Alcaraz brushed aside Roman Safiullin, the Russian playing in Paris as a neutral, 6-4, 6-2. Nadal, who has won 14 of his 22 Grand Slam titles at Roland Garros, exited Paris after he and Alcaraz were defeated in the men’s doubles, going down 6-2, 6-4 to US pair Austin Krajicek and Rajeev Ram. The 38-year-old Nadal, a two-time Olympic gold medallist, walked off Court Philippe Chatrier applauding all four sides of the stadium. The injury-plagued former world number one, with his ranking now at 161, has said he will make a decision on his future in the sport after the Games. In the women’s singles, world number one Iga Swiatek overcame being struck in the body by a full-blooded backhand from Danielle Collins before her American rival retired injured in the final set. Swiatek will face China’s Zheng Qinwen, who ended the career of former world number one and three-time major winner Angelique Kerber. The 37-year-old Djokovic has only ever collected a bronze at the Olympics, at Beijing 16 years ago, but he was rarely troubled by his 70th-ranked opponent. “Bringing a medal to Serbia is always a big goal of mine,” said Djokovic, who has won three of his 24 Grand Slam crowns on Paris’s famous red clay. Djokovic, who breezed past old rival Nadal in the second round, goes on to face 11th-ranked Stefanos Tsitsipas. Djokovic boasts an 11-2 head-to-head record over Tsitsipas, including a victory from two sets down in the 2021 French Open final. “I’ve erased it,” said Tsitsipas when asked to recall that heartbreaking defeat. French Open and Wimbledon champion Alcaraz has also yet to drop a set in Paris and coasted by 66th-ranked Safiullin in 90 minutes. “The conditions were really tough with the heat and it was really humid,” said Alcaraz. Up next for Alcaraz is Tommy Paul, the American he defeated in the Wimbledon quarter-finals. Russia’s Daniil Medvedev, appearing as a neutral and seeded to face Alcaraz in the semi-finals, was defeated 6-3, 7-6 (7/5) by Felix Auger-Aliassime. Defending champion Alexander Zverev eased into the last-eight with a 7-5, 6-3 win over Alexei Popyrin. Four-time French Open winner Swiatek racked up her 25th successive win on the clay courts of Paris but only after being pole-axed by a fierce backhand from Collins in the first game of the deciding set. Swiatek took evasive action but was still struck a painful blow on her upper body. She crouched on the ground, catching her breath before continuing. Collins immediately crossed to Swiatek’s side of the net to apologise. Swiatek swept the first set 6-1 before Collins claimed the second set 6-2. However, Collins retired with an injury trailing 4-1 in the decider. Collins then appeared to exchange angry words with Swiatek at the net, later accusing the Pole of being “insincere” over her injury. Swiatek said that when she was hit by Collins, she “couldn’t breathe for some time”. Australian Open runner-up Zheng became the first Chinese woman since Li Na in 2008 to reach the semi-finals with a 6-7 (4/7), 6-4, 7-6 (8/6) win over Kerber. Zheng unleashed 64 winners to send the 36-year-old former world number one Kerber, a silver medallist at the 2016 Rio Games, into retirement. “What can I say? I gave everything,” said Kerber. Anna Karolina Schmiedlova is the first Slovakian player to make the Olympics semi-finals since Miloslav Mecir won the men’s title at Seoul in 1988. The 67th-ranked Schmiedlova stunned Wimbledon champion Barbora Krejcikova in straight sets and will next face either Ukraine’s Marta Kostyuk or Wimbledon semi-finalist Donna Vekic of Croatia.