Mark Allen came from 3-1 and 4-2 down to beat world number four Trump 6-4 and book his place in the quarter-finals of the UK Championship at the Barbican Centre.
Trump led 3-1 despite a 98 from Allen in frame three and remained clear at 4-2 before Allen pulled one back.
Both players had chances in a scrappy eighth frame, Allen responding to one of Trump’s misses by hugging his opponent as he returned to his chair.
It came down to the black and after Trump missed a tough pot with the rest and then pushed the ball over the middle pocket, Allen potted it to level at 4-4.
He took the next with a break of 65 and made 54 off a fluke in the 10th, before another piece of luck left Trump hampered by the blue and he handed Allen a frame-winning chance.
Trump was frustrated to lose after a performance from Allen which he described as “awful”.
The Bristolian added: “It just turned into a bit of a club game, to be honest.
“It’s frustrating because I felt like so far, I’ve played the best snooker in the whole tournament.”
Allen agreed with Trump’s assessment and said: “I don’t know how I’ve won that game, to be honest.
“I was very nervous and edgy before I went out, really shaking, which was strange.
“I never settled and the match was a comedy of errors. I don’t know how I won the game. Judd should have had me dead and buried.
“I never gave up though and a fluke in the final frame helped. You never know what can happen in this game.”
Stuart Bingham beat Ireland’s David Morris 6-1.