Former world champion Peter Ebdon held his nerve in the deciding frame to beat world number one Neil Robertson at the International Championship in China.
The Englishman, 43, saw a 5-3 lead slip before clinching a 6-5 victory over Australia's Robertson in Chengdu.
Ebdon will face the in-form Ding Junhui in the last eight after the Chinese star beat Welshman Matthew Stevens 6-1.
Ding is trying to become the first player since Stephen Hendry in 1990 to win three consecutive ranking events.
"I tried to play more quickly today," said Ebdon.
"I've already had a few messages from people back in the UK saying I look better when I'm getting on with it. I felt as if I was competing.
Robertson said: "I guess it's a shame I didn't get to play Ding in the quarter-finals as we're the best two players in the world at the moment.
"If Peter plays Ding and plays like he did today, I think he will probably win. Ding will have to be very patient and maintain a good temperament."
Mark Selby, the reigning UK and Masters champion, beat fellow Englishman Stuart Bingham 6-1.
He will play Marco Fu in the quarter-finals after the Hong Kong player defeated Chinese 16-year-old Zhao Xintong 6-2.
China's Liang Wenbo backed up Tuesday's win over Ronnie O'Sullivan by beating England's Mark Davis 6-1, and he will next play Scotland's Graeme Dott, who beat Norwegian Kurt Maflin 6-5.
Englishman Joe Perry beat Mark Allen of Northern Ireland 6-4 to set up a clash with Welshman Ryan Day, a 6-3 winner over Ireland's Fergal O'Brien.