Mark Williams punched his cue out of frustration in a rare display of emotion during his tense World Championship semi-final. The Welshman was chasing Judd Trump's 8-6 lead when his error allowed his opponent back into the 15th frame.

Williams had raced into a 47-point lead in the frame as he attempted to close the deficit to only one frame. The 50-year-old lined up what seemed like a simple red. However, the red ball rebounded off the jaw of the bottom-right pocket and rolled away. It was a sloppy error that allowed Trump to attempt to go three frames clear - although the 35-year-old ultimately failed to do so.

Visibly angered by his own mistake, the usually calm Williams hit his cue and stormed back to his seat. He looked furious as he sat down.

BBC commentator Dennis Taylor said: “He’s annoyed with himself. He’s given the cue a good old bashing there and you don’t see that very often from Mark Williams but he’s seething. He was going along so well. You never see Mark reacting like that. He hit the cue a few times, even after that one.”

The match had been extremely tight during Thursday's evening session. They exchanged frames until Trump earned a 5-3 lead with the final frame of the session.

After Williams' error, Trump racked up a score of 47, levelling with his rival. Williams returned to the table but fouled, failing to hit a red at the bottom end of the table. His retake of the shot saw him hand control back to Trump., but The Ace failed to see out the frame.

Regrouping following his succession of errors, Williams held his nerve to pot his way to winning the frame. He sunk the brown and then a tricky blue before rounding off the frame with the pink.

Taylor said: “What bottle this Welshman has! An unbelievable finish to that frame and we have a cracker on our hands.”

Seven-time world champion and pundit Stephen Hendry added: “This is why Mark Williams is my hero. After all that safety, a 35-minute frame, and he still has the talent and composure. Magnificent.”

Williams is the oldest player to ever play in the World Championship semi-final. He defeated John Higgins 13-12 in the quarter-final.