Ryan Day fought back from 3-0 down to knock out former champion Ding Junhui at the Dafabet Masters on Monday.
World number four Ding, winner in 2011, had breaks of 111 and 58 in his fast start at Alexandra Palace but centuries in the fifth, sixth and 10th frames secured an impressive 6-4 win for the world number 17 from Wales.
Ding follows Mark Selby out of the competition, with the reigning world champion beaten by Mark Williams on Sunday.
World number three Judd Trump had to hold off a fightback to claim his place in the quarter-finals.
Trump led 5-1 against Liang Wenbo, who rallied with back-to-back centuries before eventually losing 6-4.
Liang, ranked 19th in the world, was on course for a 147 in the second frame before missing the 11th red, but then sat and watched Trump reel off the next four frames.
Liang hit back with two half-century breaks in the seventh frame, a tournament-high 139 in the next and 116 in the ninth to pull within one frame, but Trump got over the line thanks to a break of 85