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.
Germany started brightly on home soil and created the first chance of the game as Toni Kroos' cross into the box allowed Thilo Kehrer to test Spain goalkeeper David de Gea in the 11th minute.
He said he was looking forward to battling for his place alongside players such as Paul Pogba, Bruno Fernandes, Nemanja Matic and Fred.
"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.
In the second minute after kick-off, Rondon scored the opener with his left foot. Rondon extended the lead for Dalian in the 29th minute, as he assisted Marek Hamsik to slot home.
Garcia now faces No. 28 seed Jennifer Brady of the United States as she looks to reach the round of 16 for the first time. Enditem
Germany took the reins and pressed forward whereas Spain looked shocked and unable to respond.
"It was a delight to wear yellow. Hopefully I'll keep for a few more days. Let's first see how it goes tomorrow."
LONDON, Sept. 3 (Xinhua) -- Real Madrid's Welsh international forward Gareth Bale says he would be open to returning to the Premier League but insists that so far Real Madrid have blocked his attempts to leave.
The academy, named after one of the country's most famous coaches, is solely responsible for the highest available coaching license.
"Prize money and allowances have been equalled for men's and women's football, which means female players will earn the same as the men," Brazilian Football Confederation (CBF) president Rogerio Caboclo said in a virtual news conference.