As O’Sullivan and Carter walked past each other at the side of the table, their shoulders collided.
Carter wore a wry smile on his face while O’Sullivan looked far from impressed as he sat down in his chair.
The pair then exchanged some heated words which had to beinterrupted by the match official.
“Alright fellas, just play on,” the referee said.
Five-time world champion O’Sullivan could then be heard saying: "I'm cool as a cucumber."
Snooker legend Dennis Taylor, commentating for the BBC, added: “It looked like it was a bit funny there but it’s far from funny.”
Prior to their last 16 showdown in Sheffield at the Crucible, Carter issued a stern warning to the Rocket.
The world No.15 said: "Beating me in two finals, Ronnie is the man who has stopped me doing what I most want in my career, winning the world title.
"In the four times I have played him at the Crucible he has played really well against me every time.
"But he doesn’t play badly against anyone at the Crucible, that is why he has won it five times. It certainly isn’t luck or a coincidence.
"Frankly it is nice to have another crack at him and I’d love to play him every year in Sheffield.
"We have all heard the hints at retirement over the years, but he will be playing for a long while yet, don’t worry about that.
"The threats to quit have been a bit smoke and mirrors for the last 25 years, so what is likely to change. A lot of people out there buy it, us players never have."
