The 33-year-old striker, who came on after the interval, latched onto a through pass from teammate Wu Xi before sending it into the net in the 65th minute.
Members of the US women's team filed a lawsuit against their federation in March because of alleged discrimination over wages. A federal judge ruled against the players, who have since lodged an appeal.
"It was anybody's game really for a set and a half. I made some breaks and then obviously after winning the second set I felt more comfortable. I was returning better, I started to read his serve better, and I was pleased with my serve. Overall, it was a very good test, and I am happy to get through," said Djokovic, who is bidding to capture his fourth US Open trophy and 18th Grand Slam title.
Djokovic will face Jan-Lennard Struff for a spot in the round of 16. The German needed one hour and 40 minutes to move past American Michael Mmoh 6-2, 6-2, 7-5.
Garcia looked untouchable in the first set and for much of the second, blasting 30 winners and breaking Pliskova's serve three times en route to a 6-1, 7-6 (2) victory.
There were also second round wins for fourth seed Stefanos Tsitsipas of Greece, fifth seed Alexander Zverev of Germany and seventh seed David Goffin of Belgium.
"It's a great motivation for me to want to do well this tournament, but for the most part I feel like I've been in quarantine and practising for so long, so I prefer to play matches," Osaka said.
Duan Liuyu sent a long-distance shot off the cross-bar in the 45th minute, while Marouane Fellaini saw his header hit the post in frustration in the 61st minute. Enditem
PP Sports, owned by Chinese retail giant Suning Group, had signed a three-year deal with Premier League in 2016. The broadcaster has reportedly withheld a payment of 160 million pounds rights fees which were due to happen in March.
"In the end it got too dark to go for 6.15 meters and I felt it was unsafe to continue any further," said the world silver medalist. "I felt I was in the zone. But you have to be prudent."
A source told Xinhua, they have paid 50 percents of the negotiated fees at the initial stage of the three-year circle.