World number one Judd Trump suffered a second-round exit at the Xi'an Grand Prix in China following a dramatic 5-4 defeat to Matthew Stevens.
Trump, who made a maximum 147 break in his first-round win over Ng On-yee, looked on course to progress after moving 3-1 ahead courtesy of a knock of 84.
But last year's runner-up then required snookers and a respotted black to force a decider after former Masters and UK Championship winner Stevens claimed three frames in a row to lead 4-3.
Veteran Welshman Stevens - a two-time world finalist, who sits 51st in the world rankings - held his nerve in the final frame to book a spot in the last 32, where he will face China's Lyu Haotian.
Ronnie O'Sullivan eased into the last 32 with victory over Yao Pengcheng.
The seven-time world champion – playing in his first tournament since losing the Saudi Arabia Masters final to Neil Robertson in August – triumphed 5-1 to set up a last-32 meeting with Stephen Maguire.
O’Sullivan opened with a break of 63 and then doubled his advantage with a superb clearance of 128.
World number 118 Yao halved his deficit thanks to a break of 55 and had chances to level before O’Sullivan reasserted his authority to progress in relatively straightforward fashion.
Northern Ireland's Jordan Brown was beaten 5-1 by Ding Junhui.
Teenager Stan Moody held off an Ali Carter fightback to win 5-3. The 19-year-old will take on 2015 world champion Stuart Bingham in round three.
Mark Allen is in action now against Oliver Lines.
