China's Zhang Zhizhen stunned third seed Daniil Medvedev 6-3, 2-6, 7-6(5) to reach the quarterfinals at the Terra Wortmann Open in Halle, Germany on Wednesday.

The Chinese No. 1 was trailing 3-5 in the tiebreaker of the third set, but rallied four points in a row for his second Top 5 victory, after defeating Casper Ruud at last year's US Open.

"A really tough match. Last time I lost a third-set tie-break [in Stuttgart last week]. And today again, a third-set tie-break. I was thinking, 'Okay, it's time. The perfect moment to get revenge'," Zhang was quoted as saying by the ATP official website. "I'm super happy that today I handled it to the end."

Zhang will next play Christopher Eubanks of the United States, who shocked defending champion Alexander Bublik 7-6(5), 4-6, 6-3.