Novak Djokovic crushed Rafael Nadal 6-1, 6-4 in their blockbuster Olympics clash on Monday as the two titans met for the 60th and possibly final time.

The showdown between the two most successful men's tennis players in history appeared to be fizzling out, before Nadal staged a late fightback to avoid his heaviest-ever defeat by Djokovic.

"I'm very relieved," said Djokovic. "Everything was going my way, I was 6-1, 4-0 up, but I played a sloppy service game and gave him chances."

It was 24-time Grand Slam champion Djokovic's 31st win in a rivalry that began on the same clay of Roland Garros in 2006.

"You could feel the tension coming into the match, but also the incredible hype, the incredible atmosphere on the court," said Djokovic.

"I never thought, back in 2006, that we'd still be playing each other almost 20 years later."

Nadal admitted Djokovic was the "clear favorite" ahead of their first clash in more than two years, with the Spaniard a shadow of the player who reigned for the best part of two decades at Roland Garros.

While 14 of Nadal's 22 Grand Slams have come in Paris, the 38-year-old has been plagued by injuries in recent years, and he has slumped to 161st in the world.

His participation in the singles in Paris had been in doubt until the last minute.

Djokovic, too, has not had a good season by his high standards, but the 37-year-old Serb rose to the occasion in his pursuit of an elusive Olympic gold.

The top seed raced into a 5-0 lead before Nadal finally got on the board, but Djokovic closed out the set and surged 4-0 ahead in the second. That was when Nadal finally offered some resistance.

Nadal clawed his way back to 4-4, only for Djokovic to break once more, this time making no mistake as he put away his old foe, and perhaps brought down the curtain on one of the greatest rivalries in the history of the sport.

"When this tournament is over, I will take the necessary decisions based on my feelings and desire," Nadal said regarding his future in tennis.

Djokovic, a bronze medalist on his Olympic debut in 2008, goes on to face Dominik Koepfer of Germany for a spot in the quarterfinals.

Nadal will turn his focus to the doubles, where he is in a "dream team" pairing with compatriot Carlos Alcaraz.

Alcaraz, the reigning men's French Open and Wimbledon champion, saw off Dutchman Tallon Griekspoor 6-1, 7-6 (3) after saving a set point and receiving treatment for an apparent upper leg injury.

Russian, Roman Safiullin will be his next opponent.

Unstoppable Swiatek

Women's world No 1 Iga Swiatek took another step on her quest for gold by powering into the third round.

Swiatek, tested in her opening match under the roof on Court Philippe Chatrier, enjoyed a far more straightforward outing in the bright sunshine on Monday.

The four-time French Open champion underlined her status as the heavy favorite in Paris, swatting home hope Diane Parry aside 6-1, 6-1 to set up a meeting with China's Wang Xiyu for a place in the quarterfinals.

The Pole has won her past 23 matches at Roland Garros, with three clay titles already under her belt this season.

Elsewhere, United States second seed Coco Gauff dispatched Argentina's Maria Lourdes Carle 6-1, 6-1. Next up for her is Wimbledon semifinalist Donna Vekic, who put out former US Open champion Bianca Andreescu.

Italy's Jasmine Paolini, this year's French Open and Wimbledon runner-up, eased into the third round with a 6-4, 6-1 victory over Magda Linette.

Wimbledon champion Barbora Krejcikova coasted past China's Wang Xinyu, while Maria Sakkari of Greece also advanced.

Zheng Qinwen, Stefanos Tsitsipas and Casper Ruud were among other second-round winners.

AFP