Novak Djokovic is into the last eight at the Paris Olympics after he cruised past Dominik Koepfer in straight sets. (Full Olympics Coverage | More Sports News)
Djokovic triumphed 7-5 6-3 in one hour and 37 minutes at Roland-Garros on Wednesday.
The world number two is in the hunt for a second Olympic medal, having previously claimed bronze in 2008.
Stefanos Tsitsipas, who beat Sebastian Baez, is next up for Djokovic.
The 37-year-old, now into his fourth Olympic quarter-final, has defeated the Greek in each of their last 10 meetings.
"It’s very humid," said Djokovic after his win, with Paris experiencing sweltering conditions.
"I just hope it rains so it cools down the temperature and the air a bit. But you have to accept and embrace the conditions. It's the same for you and your opponent, so you have to make the best out of it."
Lorenzo Musetti, meanwhile, defeated Taylor Fritz, though the latter's compatriot Tommy Paul did beat home hope Corentin Moutet.
Data Debrief: Golden oldie
At the age of 37 years and 61 days, Djokovic is the oldest player to reach the men's Singles quarter-finals at the Olympics since tennis returned to the program in 1988.
Italian Musetti has equalled the best run by a man from his nation in the Olympics singles since 1988 (Paolo Cane in Seoul 1988 and Renzo Furlan in Atlanta 1996).
