Controversy hit the Betfred World Championship final as tension built at the Crucible.
Mark Selby, leading John Higgins 16-14, looked to play a snooker behind the black but was ruled to have trickled up short.
Referee Jan Verhaas called a foul, before briefly going back on his decision after seeking advice from Steve Davis and John Parrott in the BBC studio inside the theatre.
They and Brendan Moore, the referee who was on scoring duty, could not agree a definitive decision though and Verhaas elected to stand by his original decision.
Selby looked unimpressed, while Higgins went on to win the frame and close to 16-15 behind.
Big moment in the 31st frame— Eurosport UK (@Eurosport_UK) May 1, 2017
Referee Jan Verhaas calls a foul, replays suggest it hit, but he sticks with his original decision. Thoughts? pic.twitter.com/QmqIObNFGV
Here is a transcript of the conversation involving Verhaas, Selby and Higgins.
Verhaas: Foul. Did it hit? I didn't see it hit, Mark.
Verhaas: No. Mark Selby, one. John Higgins, seven. Free ball.
Higgins: Can we have a replay?
Verhaas: We can't have a replay John. I honestly didn't see it hit.
Selby: It looks like it hit.
Verhaas: It hit? Okay, okay.
Selby: Do you want to have a look, John?
Verhaas: No, if they say it hit then it's fine with me. Mark Selby, one, then. I'm good with that.
Guys? Well, if they're not sure, honestly I didn't see it hit. I'm going to stick with my original decision then. I'm going to stick what I saw and I didn't see it hit, so I'm going to stick with the 'foul, seven'. Okay?
Selby currently leads 17-15.