Four years ago, Stephen Maguire and Shaun Murphy fell out over an incident at the Grand Prix.
Maguire was about to break off in the first frame when he realised he had forgotten his chalk.
He was granted permission by the referee, Johan Oomen, to go and get some chalk from his dressing room.
While he was out of the arena, Murphy approached Oomen to remind him that players should be docked a frame if they are not ready to play at the scheduled time.
The tournament director, Mike Ganley, was called and Maguire was docked a frame on his arrival back at the table.
He won the match but hasn't forgotten the incident.
It doesn't change what he thinks of Murphy as a player but the chances of them forming a doubles partnership appear just as remote now as they were in 2004 when this incident occurred.
“As snooker players, Shaun and myself respect each other. It would be hard not to because he’s a great player," Maguire told me today.
“We’re not best of friends but that adds an extra edge when we play each other because we want to beat each other so much.
“I enjoy that. You can’t be friends with everyone."
I agree that sport needs rivalries and grudge matches.
Why should all the players be friends?
Maguire's 10-9 victory over Murphy in this year's China Open final was probably the best match of last season.
Stephen's right that the additional spice that comes when they play makes their clashes that little bit more special.
The truth is that Maguire and Murphy are different types of people.
And snooker is all the better for it.