After Osaka lost her serve again to end the match by hitting a cross-court backhand wide, she shook hands with Vondrousova at the net, walked to her chair, zipped her racket up in her bag and followed Vondrousova off the court.
23-time Grand Slam singles champion Serena Williams to skip Tokyo Olympics
Djokovic, who previously won at Roland Garros in 2016, has become the first man to win all four Grand Slams twice since the fully professional Open era began in 1968.
Both women had worked hard to get to the main stage at Roland-Garros.
Djokovic's victory extended his advantage in the head-to-head with Nadal, having claimed his 30th win in their men's record 58th meeting.
Six-time major champion Boris Becker suggested this week that the end of Nadal's reign in Paris is a question of time amid his pursuit of a fifth successive French Open crown. Novak Djokovic could have a defining say in that after overcoming Matteo Berrettini 6-3 6-2 6-7 (5-7) 7-5 to seal his place in the final four and pencil in a semi-final match-up with his old foe.
