Barry Hawkins hailed one of the best wins of his career after holding his nerve to edge Ronnie O'Sullivan in a final frame thriller and reach the World Championship quarter-finals.
Hawkins saw a 12-9 lead evaporate as the five-time world champion launched a sensational fightback to level but the 37-year-old carved a break of 56 out of a scrappy final frame to nudge over the line.
His 13-12 victory gave Hawkins his first win over O'Sullivan in 14 years -- and came just three months after he was humiliated 10-1 by the same player in the Masters final at Alexandra Palace.
"It's definitely up there," said Hawkins. "It's so tough, intimidating playing Ronnie out there and not many people can beat him over three sessions, so it is a massive confidence boost and proves I can compete with anyone.
"I was feeling the pressure big-time, but especially in the way he came back at me. He just makes it look so effortless at times and it winds you up -- there's me twitching about and he's just flowing.
"I knew I had to play really well but I definitely had a different mindset from going into the Masters final. I'm just delighted to get another victory over him after 14 years -- it might be 14 years before I beat him again."
O'Sullivan's stunning one-visit snooker looked set to pay off as breaks of 124 and 92 -- made up of 11 reds and 11 blacks -- set him on the way to clawing back a 12-9 deficit.
Of the 12 frames ultimately won by O'Sullivan, he scored four centuries and a further seven winning breaks of over 50, but the five-time champion admitted the fact his safety game was not up to scratch cost him dear.
O'Sullivan said: "I fancied my chances but when a frame goes like that it's a bit of a toss of a coin and if there was a weakness in my game it was definitely on the tactical side.
"I was second best in 90 or even 100 percent of every frame that went like that, and if it wasn't won in one visit I probably lost all of them. I feel like a golfer birdying 15 holes but taking triple-triple bogeys on three holes."
The manner of O'Sullivan's defeat -- which was sealed by an unfortunate in-off which scuppered any final chance he had of rescuing the deciding frame -- clearly hit him hard and he revealed all was not well behind the scenes.
Referring to his failure to attend a press conference following his first-round win over David Gilbert, O'Sullivan said: "I don't want to go into detail. I wasn't in a fit state to really come in.
"I find it difficult being a figurehead of the sport with all the attention on me and such a high expectation on me, including from myself, and sometimes I don't handle that well.
"Hopefully with a bit of help and support I can manage the pressure and stress I put on myself and that comes from you guys as well, because you kind of make out I've won the tournament before I even turn up."
Hawkins will next face Marco Fu in the last eight while rising star Kyren Wilson will take on world No.1 Mark Selby after enhancing his credentials by completing a 13-9 win over Mark Allen.
The 24-year-old all but booked his place in next season's top 16 with his victory, and has now set his sights on becoming the first qualifier to win the title since Shaun Murphy in 2005.
Wilson said: "It was obviously a fantastic achievement the way Shaun blitzed everyone with his sensational potting, so he's proved that it's possible and I'd love to add myself to that list.
"That match took a lot of mental strength but I think it set me up nicely for the next round. I've shown I can mix it, I can flow and I can battle. What ever my opponent throws at me I'm capable of dealing with it."
Judd Trump was another high profile casualty on Monday with the former finalist failing to claw back an overnight deficit against Ding Junhui, eventually falling to a 13-10 defeat.
Afterwards Trump denied his social media activity had been a factor in his defeat, having sent a number of tweets during mid-session intervals earlier in the tournament including one taking issue with comments made by fellow professional and current television commentator Dominic Dale.
Trump said: "It worked when I was 7-6 down to [Liang] Wenbo -- I came back and played really well and I didn't miss a ball.
"This time I lost because Ding was the better player -- there's no other reason. I don't want to drain myself thinking about the game all day, every day."
Four-time champion John Higgins completed the quarter-final line-up with a 13-8 win over Ricky Walden, and will face fellow Scot Alan McManus starting on Tuesday.