Novak Djokovic outclassed his long-time rival Rafael Nadal to win their Olympic second-round match and continue his bid to land an elusive gold medal.

Serbia's Djokovic, 37, looked on a different level to Nadal for most of a one-sided contest which he won 6-1 6-4 on the Roland Garros clay.

Djokovic led 4-0 in the second set to quell the partisan support for the Spaniard, before 38-year-old Nadal fought back to wipe out the double break.

But Djokovic, like we have seen him do so many times, stepped on the gas again to break for 5-4 and serve out victory.

"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."

Nadal, known as the King of Clay, has won 14 French Open titles at the Olympic venue but the aura he carries there was not enough to trouble a man of Djokovic's quality.

The pair, who have won 46 Grand Slam singles titles between them, shared an embrace at the net before Djokovic sportingly clapped Nadal off the court.

It was the 60th meeting of their enduring rivalry - no two men have ever played each other more.

After first meeting in 2006, Djokovic now leads 31-29 in their head to head.

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