UK champion Judd Trump suffered a shock 13-12 defeat after a great comeback by Ali Carter in the last 16 of the World Championship at the Crucible.
Resuming 9-7 up, last year's losing finalist Trump edged to within a frame of victory at 12-9.
However, world number 17 Carter bravely fought back to force a decider and then won a scrappy final frame to secure an unlikely victory.
Matthew Stevens also beat Barry Hawkins 13-11 to advance to the quarter-finals.
Carter, who reached the final in 2008, will play either Jamie Jones in the last eight, while Stevens will face Ryan Day after the Welshman beat Cao Yupeng in the second round.
"I'm delighted to get through," Carter told BBC Sport. "All credit to Judd. He pots them from everywhere, but there's more to this game than potting balls from everywhere as I've shown today."
After potting a crucial colour in the deciding frame, Carter punched the air only to make a mistake on the next red which let Trump back in, albeit it needing snookers.
"I've got a lot of experience," he added. "I shouldn't have done the fist-pump but I thought I was home and dry.
"I played a bad shot on the last red. If I had concentrated on getting a good safety, I would have won easy, but it makes it all more sweeter as I had to suffer even more."
World number two Trump was one of the favourites coming into the tournament and looked in fine form as he won six of the afternoon's eight frames on Sunday to transform a 5-3 overnight deficit against Ali Carter into a 9-7 lead.
The 22-year-old left-hander started the final session strongly, winning the opener before being pegged back by Carter, who knocked in a break of 70.
A break of 96 increased Trump's lead to three one more, but Carter refused to be beaten and a knocked in a break of 94 to make it 11-9.
Trump won a scrappy 21st frame to move to within one of victory, but Carter clung on with a break of 81.
Carter won the next to force a decider, which turned into a marathon as both players made mistakes under pressure.
Trump had his chances after Carter's break broke down, and at one stage came to the table needing four snookers. However, it wasn't to be.
In the afternoon's other match, two-time Crucible runner-up Matthew Stevens reached the last eight with a scrappy 13-11 win over Barry Hawkins.
Resuming at 8-8, Stevens moved two frames in front before Hawkins pegged him back at 10-10.
The next three frames were scrappy, with Stevens emerging with a 12-11 lead before a break of 57 sealed the match.