Zhang Anda produced a superb potting display to defeat world champion Zhao Xintong 6-2 as he advanced to the last eight at the UK Championship in York.
Having lost the opening frame of the all-Chinese affair, Zhang hit back-to-back centuries as the first four frames were shared.
But Zhao, who was guilty of missing several routine pots, was heavily punished by his compatriot when play resumed after the interval.
Zhang was near faultless among the balls and reeled off their next three frames with breaks of 87, 69 and 73 before rounding off his victory in a nervy eighth frame.
"I played so well, there were three frames where I scored heavily and Xintong did not play well. It was my day," Zhang told BBC Sport.
"In the first session I made two centuries and it was very good stuff from me. In the fourth frame I missed some simple shots but I told myself to forget it, I am playing well, I can beat him."
The 33-year-old, who has now reached three consecutive quarter-finals at the tournament, will face either John Higgins or Shaun Murphy next.
Even though Zhang had defeated Zhao in their only previous competitive meeting a decade ago, he was still regarded as the outside chance going into this contest.
While both practice at the same Sheffield academy, their careers have run on different paths.
Zhang has slipped out of the top 16 in the world rankings, while Zhao, who announced himself on a global stage by winning the UK title in 2021, has gained "megastar" status since becoming the first player from China to triumph at the Crucible in May.
It was a feat all the more remarkable given he was one of 10 Chinese players sanctioned in 2023 following an investigation into match-fixing and served a 20-month ban.

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