Spain's Carlos Alcaraz has joined 24-time Grand Slam champion Novak Djokovic in the Olympic men's singles quarter-finals. But Alcaraz and 14-time French Open champion Rafael Nadal were beaten in the men's doubles by USA's Austin Krajicek and Rajeev Ram - losing 6-2 6-4. French Open champion Alcaraz defeated Russian Roman Safiullin, who is competing as an Individual Neutral Athlete, 6-4 6-2. Earlier, Djokovic beat Germany's Dominik Koepfer 7-5 6-3 in very humid conditions, as the Serb continues his quest for the Olympic men's singles gold that has so far eluded him.
French Open finalist Alexander Zverev overcame a spirited start by Australia's Alexei Popyrin to reach the last eight.
The quarter-final line-up also includes Greece's Stefanos Tsitsipas, Canada's Felix Auger-Aliassime, Italy's Lorenzo Musetti, Norway's Casper Ruud and the USA's Tommy Paul.
French Open women's champion Iga Swiatek went through – having been tested in her quarter-final. She was leading 6-1 2-6 4-1 when the USA's Danielle Collins retired in the deciding set.
Germany's three-time Grand Slam champion Angelique Kerber's career finally came to an end, after losing to China's Zhang Qinwen 6-7 (4-7) 6-4 7-6 (8-6).
"I've achieved everything I dreamed of," Kerber said. "I was number one, won Grand Slams, won a (silver) medal in Rio, so what more could you want in the end?"
Kerber triumphed at the 2016 Australian and U.S. Opens before claiming the Wimbledon title two years later.
