Aaron Hill stunned Judd Trump by beating the world number two 4-1 at the Northern Ireland Open on Tuesday.
Trump had been level with the 20-year-old before the Irishman won the last three frames, including a break of 87.
The 20-year-old Cork native had a break of 52 to win the opening frame during the evening session before Trump took the second.
But Hill then took the third and had a break of 87 as he won the fourth. He then showed great composure to take the fifth to secure victory.
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Speaking after his win, Hill said: "It's an absolutely brilliant feeling. I was staying positive the whole match and I said I'd rather go out by missing something than playing defensive so I played my own game from the get go - attacked, played some good snooker.
"I'm really happy with how I got over the line there. I'd a tricky yellow to the middle and instead of putting a colour safe or sticking up behind the yellow, I went for it so I'm really happy with the way I finished the match."
Hill will face Tom Ford in a last 32 on Wednesday night.
Meanwhile, John Higgins came from behind to beat Jackson Page 4-3 after mounting a late comeback in the sixth and seventh frames.
Earlier in the match Page had made a 128 clearance to level at 1-1.
However, in the sixth frame, he missed a red to allow Higgins to clear up and force a decider, which he then won with a 124 break.
Barry Hawkins confidently booked his place in the fourth round with a 4-0 win over Louis Heathcote.
Shaun Murphy was also comfortably through with a 4-1 win over Jamie Rhys Clarke.
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