Two-time winner John Higgins was knocked out of the Dafabet Masters in the first round following a thrilling 6-5 defeat to Mark Allen at Alexandra Palace.
Higgins, who last won the tournament in 2006, missed crucial yellow and blacks when he was in the balls at 5-5, giving Allen the opportunity to avenge defeat in the UK Championship.
Higgins took an early lead, claiming the first frame before firing in a 111 break, only for a dogged Allen to draw level.
The two continued to trade blows before Allen took the lead for the first time with breaks of 81 and 104, setting up a pivotal ninth frame.
After making 67, Higgins forced a respot on the black, and after a series of safety shots, Allen stepped up to pot it from range and claim a 5-4 lead.
Higgins again drew level, but after the Scot missed a black off its spot Allen stepped in to claim a thrilling match and move into the quarter-finals.
Allen told worldsnooker.com: "It was very tense in the last. I noticed John shaking quite a bit. Him missing the black off the spot was unexpected - but not so much to me.
"It shows how much it means to John considering what he's done in the game. It was just one of those matches you didn't want to lose. One thing I have always had is bottle."
In the night's other match, Joe Perry cruised to a 6-1 win over world number two Stuart Bingham.
Perry got off to a flyer with a break of 116, before stealing the second frame on a respotted black.
Bingham got himself back into the match with a superb 132, but breaks of 77, 76 and 107 set Perry on the way to a quarter-final spot.