The last set became a lop-sided affair for Tianjin, which went on a 12-4 run to pull away and kept the advantage until the end.
Elsewhere, Santos rallied late to secure a 3-2 win at Goais. Marcos Leonardo, Jefferson and Marinho were on target for the visitor while Vinicius Lopes and Victor Andrade scored for Goias.
The result has increased the pressure on Athletic Bilbao coach Gaizka Garitano, whose post-match comments that "the Primera Liga is difficult for us" was criticized by the fans.
"We didn't perform well in the first quarter. We had a tough start, but ultimately took our chance," Shaanxi coach Jiang E'Ying reflected.
Khachanov won the pair's previous encounter in Paris - at 2018 Paris Masters, when the Russian claimed a straight-set win in the final to clinch the biggest title of his career until now.
Shaanxi's Chen Yanyu registered a double-double of 29 points and 11 assists. Her backcourt partner Chen Xinlei pocketed 28 points.
In other games in Chengdu, after a goalless first half, Beijing Renhe broke the deadlock in the 57th minute to claim a 2-0 victory over Suzhou Dongwu. Taizhou Yuanda defeated Inner Mongolia Zhongyou 2-0.
Kvitova went into the match quickly as she broke her Chinese opponent twice to surge to a 4-0 lead in the opening set, before serving for the set in the eighth game.
Zhejiang outscored 52-37 at the interval, which proved to be a key part of their victory. Dong Ke'er made six 3-pointers to score 26 points. Huang Jiali shot 11 of 14 from the field for 26 points.
Shanxi and Henan played out a close game, although Shanxi ultimately won 76-70. Shanxi led the game by 9 points after the first half, but Henan did very well to surpass Shanxi in the third quarter.
The win, which came as the 35th from 36 matches this season, also ties him with Rafael Nadal for a record 14th Roland Garros quarterfinals appearance.