Two-time Grand Slam winner Kvitova had to bounce back from 1-5 down in the opening set against Canada's teenager Leylah Fernandez to set round-of-16 clash with Zhang.
Gaston is to challenge third seed Dominic Thiem in the fourth round. Earlier in the day, the Austrian had claimed another straight-sets victory over 28th seed Casper Ruud, beating the Norwegian 6-4, 6-3, 6-1.
His initial spell at the helm ended after the 1990 World Cup, however, Tabarez returned in 2006 and immediately turned the team's fortunes around.
1: Barca still has work to do
The second set was filled with breaks as both players failed to hold their serves from the sixth to the 11th game. Zhang served to win in the 10th game but was broken by her French opponent. However, when the chance appeared again on the 12th, Zhang didn't miss it and wrapped up the victory with a flawless love game.
On Friday Heerenveen drew 1-1 at FC Utrecht and Vitesse beat Heracles Almelo 3-0 on Saturday. Feyenoord now leads the Eredivisie with 10 points after four matches. PSV and Heerenveen also have 10 points, but Feyenoord's goal difference is better. Vitesse and Ajax are fourth and fifth with nine points. Enditem
An excellent team performance from West Ham saw them rewarded with a surprise 3-0 win away over Leicester City, who had demolished Manchester City 5-2 a week ago.
"It's been long ride definitely. Everything came to my mind when I had my whole family, people who I loved to help me through the tough, tough time," said Kvitova. "I was just playing in the Philippe Chatrier, it was such nice to win the match and to be in the quarterfinal."
"We can feel that everything is fully prepared beforehand with an aim of offering us a safe environment to enjoy games," said Shao, who had joined Sichuan before the season.
"I'm very happy. It was a great match, I didn't make any mistakes. Casper is a really great player, very attractive to play, I think there were many good rallies, it was a good match from both of us," said the recently-crowned US Open champion.
"I got a bit emotional last two points of my match. I really started to think still about the match because in tennis we really never know when it's the end. But my memories, happy memories, when I made my comeback here in 2017, when I step on the Philippe Chatrier, I couldn't really imagine me to be in the quarterfinal of this slam. Everything just came back to me," said Kvitova, who was attacked by a break-in knife-wielding robber at her home in the Czech Republic during the off-season of 2016 which left her dominant left hand seriously injured. It was at Roland Garros that the two-time Grand Slam champion made her comeback.