World No.1 Novak Djokovic brushed aside Briton Kyle Edmund 6-7 (7-5) 6-3 6-4 6-2 on Wednesday after a sluggish start to remain unbeaten in 2020 and move into the third round of the US Open.

On a hot, humid day at Flushing Meadows, Edmund was left bathed in sweat while a cool and collected Djokovic stayed on course for his 18th grand slam title and improved his 2020 match record to 25-0.

It stands as the second best start to a season since the Serb went 41-0 in 2011.

With the two other members of the sport’s Big Three – Roger Federer and Rafa Nadal – absent from the tournament, Djokovic is heavy favourite to hoist the trophy and the Serb overcame a slow start to show why.

Edmund took a tight opening set, laying down an ace to clinch the tiebreak 7-5.

It was only the sixth set Djokovic had dropped going all the way back to the Australian Open and he did not surrender another to the 44th-ranked Briton.

“I would like to say happy birthday to my daughter Tara, she’s turning three today so she gave me a lot of energy and strength, I love you darling,” said father-of-two Djokovic.

Stefanos Tsitsipas weathered a serve-volleying storm from Maxime Cressy before grinding the American wildcard down 7-6 (7-2) 6-3 6-4 to reach the third round.

In a slow-burning contest of short, sharp points, fourth seed Tsitsipas had to fight off a set point against the French-born Cressy, who thrashed down 21 aces and chipped-and-charged relentlessly.

Impressing in his main draw debut at a grand slam, Cressy dragged the Greek deep into the final set but was broken in the ninth game as fatigue set in, allowing Tsitsipas to close out a tough win on serve.

Tsitsipas will next play Croatia’s Borna Coric for a place in the last 16.

German No.5 seed Alexander Zverev fought off a spirited challenge from American wildcard Brandon Nakashima to claim a 7-5 6-7 (10-8) 6-3 6-1 win.

Zverev did not drop serve in a solid all-round display but was stretched to four sets by teenager Nakashima, who is ranked 223 in the world and coached by former 1987 Wimbledon champion Pat Cash.

“I didn’t get broken even though my second serve was shaky a little bit,” Zverev said.

“My backhand was shaky too. I will have to go practise some more.”

Young gun Denis Shapovalov was twice forced to come from behind before beating Kwon Soon-woo 6-7 (7-5) 6-4 6-4 6-2 to secure a place in the third round of the US Open for a fourth straight year.

The 12th seed was in all sorts of trouble against the unheralded South Korean, losing the first set in an error-strewn tiebreak and going 4-2 down in the third, before storming to victory by winning 10 of the last 12 games.

Belgian No.7 seed David Goffin also advanced with a 7-6 (8-6) 4-6 6-1 6-4 win over South Africa’s Lloyd Harris.

-AAP