Novak Djokovic overcame an early scare to move into the third round of the US Open Wednesday but top women's seed Karolina Pliskova crashed out in the tournament's first shock.

Djokovic extended an undefeated run in 2020 to 25 matches as Pliskova was stunned in straight sets by France's Caroline Garcia, the world number 50.

World number one Djokovic dropped the first against Britain's Kyle Edmund but rallied to progress 6-7 (5/7), 6-3, 6-4, 6-2 inside a subdued, spectator-free Arthur Ashe Stadium at Flushing Meadows.

"I'm really glad having an early kind of tough match because it kind of serves me better I think for the rest of the tournament," said Djokovic.

The Serbian superstar is looking to close the gap on Roger Federer and Rafael Nadal, both absent from Flushing Meadows, in the race for the all-time men's Slam singles title record.

The 33-year-old -- who won an eighth Australian Open title in February -- is on 17, with Nadal on 19 and Federer on 20.

Pliskova -- the 28-year-old world number three from the Czech Republic -- suffered a miserable 1-6, 6-7 exit to a confident Garcia who rushed to a 5-0 lead in the first set.

Pliskova said her defeat was nothing to do with being elevated to the top of the draw after a host of high-ranking withdrawals over coronavirus fears.

"No, zero pressure from this for me. This is nothing to do with my loss today," she sniffed.

Elsewhere in the men's draw Wednesday, fourth seed Stefanos Tsitsipas of Greece defeated American Maxime Cressy 7-6 (7/2), 6-3, 6-4 in his first runout on the famous Ashe court.

"It would have been even better with fans but getting a first taste of what it is was great for me," he said.

Earlier fifth seed Alexander Zverev defeated American wildcard Brandon Nakashima in a far from smooth 7-5, 6-7 (8/10), 6-3, 6-1 win.

The world number seven traded 24 aces with 10 double faults against a player ranked 223 inside an empty but and humid Louis Armstrong Stadium to move into round three.

"I was sweating through my shoes, which is unusual," said Zverev, explaining a footwear change during the match. "I needed to go from the dry tires to the wet tires a little bit."

Belgian seventh seed David Goffin also progressed as the top seeds continue to dominate at the Billie Jean King National Tennis Center.

- Empty tank -
In the women's draw, 2018 champion Naomi Osaka sailed into the third round, dismantling Italy's Camila Giorgi 6-1, 6-2 in just 1hr 9min.

Sixth seed Petra Kvitova vanquished Kateryna Kozlova of Ukraine 7-6 (7/3), 6-2 while Germany's Angelique Kerber beat compatriot Anna-Lena Friedsam in straight sets.

The 17th seed won 6-3, 7-6 (8/6) in one hour 40 minutes inside Louis Armstrong Stadium.

Also in the women's event, unseeded Russian Varvara Gracheva dumped out French 30th seed Kristina Mladenovic 1-6, 7-6 (7/2), 6-0.

Mladenovic's exit came after a remarkable collapse. The Frenchwoman led 6-1, 5-1 and failed to convert four match points as Gracheva came roaring back to win.

"I just collapsed," a gloomy Mladenovic said afterwards. "I had nothing left in the tank."

The US Open is taking place in a spectator-free bubble, resulting in a staid atmosphere in contrast with the usual frenetic energy that pervades the grounds of the tennis center during Open week.

Game-winning points are being met with the odd clap from coaches and admiring glances from rival players watching from their own personal suites in Arthur Ashes.

Crowd noise is piped-in between sets while images of spectators cheering from their sofas at home are shown on "fan cams" around the Arthur Ashe court.

Osaka sails into third round

Naomi Osaka sailed into the third round of the US Open on Wednesday, demolishing Italy's Camila Giorgi in straight sets.

Japanese fourth seed Osaka needed only 1hr 9min to swat aside Giorgi, the world number 74, winning 6-1, 6-2.

Osaka, the 2018 US Open champion, will now play Marta Kostyuk of Ukraine in the last 32 on Friday.

Osaka said she had set out to dominate her hard-hitting Italian opponent from out outset.

"I never want to depend on what the other person's going to do," Osaka said. 

"Even if I play a power player, for me, my goal is to be the dictator. I think that I was able to do that quite well. I think when she was hitting really hard, I was able to neutralize. When I had the chance, I went for the ball that I wanted.

"I definitely played I think the best out of the two weeks that I've been here today."

The 22-year-old Osaka had entered the tournament with concerns over her fitness after withdrawing from the final of the Western & Southern Open last week.

Her weary body was given a thorough test in her first round match on Monday, when compatriot Misaki Doi took her to three sets.

However there was no sign of fatigue from Osaka on Wednesday as she romped to victory with tightly disciplined display.

In all, Osaka finished with 14 winners and only 11 unforced errors in the win.

Her powerful service game also looked in good order, with Osaka winning 79% of points on her first serve.

Osaka entered the Arthur Ashe Stadium wearing a facemask emblazoned with the name of Elijah McClain, a 23-year-old African-American man who died in police custody last year after being placed in a chokehold and injected with a sedative.

"For me, I think when I heard about his story it was very hurtful," Osaka said of McClain. "I mean, they're all very hurtful, but just the fact of the character and the way that he was, just to hear stories about him, for me it was very sad. Today was very special in the way that I wanted to represent him very well."

Osaka, an activist against racism and police brutality, says she plans to wear different masks honoring victims of social injustice throughout the tournament.