Ronnie O'Sullivan suffered a shock 4-2 defeat against China's Zhang Anda at the BetVictor English Open.
The Rocket reached the last 16 in a close encounter earlier in the day that saw him come from 2-1 down to beat Si Jiahui 4-2.
O'Sullivan hit a break of 80 to take the first frame before Zhang levelled and the world number one was in trouble as the Chinese player won two successive frames to open up a 3-2 lead.
And Zhang sealed the upset in style, finishing off with a 125 century break to book his spot in the last eight.
World number two Luca Brecel faced a tough match-up in his last-16 clash against Ding Junhui.
The world champion beat Muhammad Asif 4-0 to set up the evening's contest, which went back and forth as Ding came from 2-0 down to tie 2-2 before snatching the fifth frame.
Brecel forced a decider but it was Ding who came out on top thanks to a break of 58.
World number five Judd Trump reached the quarter-finals with a rallying effort, coming from behind to beat Yuan Sijun 4-2, while John Higgins also secured his spot in the final eight.
The Scot did so in style with an incredible start that saw him hit a break of 145 in the first frame, setting him on the way to a 4-1 victory over Oliver Lines.
