World number one Judd Trump suffered a shock first-round defeat at the PTC Grand Finals in Galway as Alfie Burden sprung a huge surprise.
Victory saw Burden, a lowly 55 in the rankings, reach the last 16 of a full ranking event for only the second time in his career and the first since 1997.
Trump, who followed world number two Mark Selby out of the tournament, mustered a best break of 44 and made a number of mistakes around the table, while 36-year-old Burden impressed with breaks of 76 and, in the deciding seventh, 116.
John Higgins was knocked out 4-2 by a fit-again Ali Carter.
Carter, who could not take part in last month's Haikou World Open due to complications with his Crohn's disease, sealed a place in the last 16 with the win. He took advantage of a missed red to make a 79 clearance in the first frame before Higgins made it 1-1 with a run of 111. Carter then made it 3-1 and 4-2 to progress.
Chinese number one Ding Junhui reversed a 3-1 deficit to defeat Andrew Higginson 4-3.
Higginson, a semi-finalist here last year, reeled off breaks of 57 and 71 on his way to a two-frame lead but Ding changed the momentum irreversibly with a turn of 118 in the fifth.
His compatriot Xiao Guodong was also successful, securing a 4-1 win over former world champion Graeme Dott, who was in ragged form.
Rod Lawler denied China another winner on the night as he defeated Cao Yupeng 4-2. After losing the opening frame, Liverpudlian Lawler took the next three to put him on the road to victory.
In the day's final game, Norwegian Kurt Maflin beat former world champion Ken Doherty 4-2.