One of three Chinese men in the draw, Zhang became the first from the nation to win a main draw match at Roland Garros in 86 years after Serbian opponent Dusan Lajovic retired due to illness when trailing 6-1, 4-1.
Compatriots Shang Juncheng and Wu Yibing bowed out in defeat but Zhang has a big chance to go further when he takes on Argentine qualifier Thiago Agustin Tirante for a place in the third round.
That would bring him a step closer to the fourth-round mark set by Kho Sin-Kie in 1936. Kho, who was born in colonial-era Indonesia but represented China in Davis Cup, also reached the third round in 1937.
"Last year, even quallies (qualifiers) I couldn't get in," world number 71 Zhang told reporters.
"This year I'm enjoying (the) first win here.
"We have so many (people) waiting for us to get (the) first win."
In the modern era, Chinese tennis has been dominated by women, with twice Grand Slam champion Li Na becoming the country's first major winner at Roland Garros in 2011.
The men's game has been a much slower burn, with Wu Di becoming China's first singles entrant at a Grand Slam main draw in the professional era in 2013 when he lost in the first round of the Australian Open.
It took nearly another decade for a Chinese man to claim a main draw win, with Wu Yibing breaking a 63-year drought on the way to the third round at last year's US Open.
Teenager Shang followed that by reaching the second round of the Australian Open in January on his Grand Slam debut as the youngest player in the draw.
Zhang, the oldest of the Chinese trio and a relatively late bloomer, has now kept the streak alive after setting a number of tennis 'firsts' for the country in recent months.
Last October, he became the first Chinese man to crack the top 100 in the ATP's world rankings and this month became the first to reach the quarter-finals of an ATP Masters 1000 tournament at the Madrid Open.
"Now we are passing the quallies and coming to the main draw," Zhang said of the Grand Slam breakthroughs.
"That's one step, again, like a step forward.
"(Chinese) Girls have a lot of people playing. Now we (men) are more and more.
"Yeah, we are trying to catch the girls."
