It was also the 96th victory at Roland Garros for the Spaniard, who is seeking a 20th Grand Slam title to equal Roger Federer's record.
"It was a very even match, perhaps more difficult than the result showed," said Djokovic, who is seeking for an 18th Grand Slam title.
As expected, head coach Gustavo Alfaro included Fenerbahce forward Enner Valencia and teenage Sporting Lisbon winger Gonzalo Plata in his 30-man squad.
The two sides found their shooting range after the tip-ff, especially for Fujian who converted 4 of 5 shots beyond the arc, but Zhejiang managed a 31-26 lead after the first quarter.
"I think we both played really well and a really great match. She played unbelievably good, considering she is so young, she has a very bright future," Zhang commented on her opponent.
The 29-year-old has been deployed by Toffees manager Carlo Ancelotti as a free-roaming No. 10, having been shunted out wide or used in a deeper midfield role during his limited opportunities for Real Madrid last season.
The Argentinian bested Nadal in the Rome Masters quarter-finals last month for his first win against the world number two.
Also on Sunday Feyenoord was far too strong for Willem II in Tilburg. The home team went in front through Vangelis Pavlidis, but Ridgeciano Haps, Bryan Linssen and a brace by captain Steven Berghuis earned Feyenoord a convincing 4-1 win. AZ drew 4-4 at Sparta after surrendering a 4-0 lead in Rotterdam.
Vanderlei Luxemburgo's men are now third in the 20-team Serie A standings, just two points behind leader Atletico Mineiro, who has a game in hand.
"The quality of our defense slumped in the second quarter, and they pulled away from the match. We can be better than this," Fujian coach Gong Songlin commented. Enditem
As one of title contenders going into the current campaign, Xinjiang was back on a winning track following its defeat to Sichuan in Thursday's opener.