Ronnie O'Sullivan started his UK Championship campaign with a 6-2 win over Daniel Wells achieved despite playing with a broken ankle.
The Rocket, who suffered the injury while out running, beat amateur Wells at York's Barbican Centre on Thursday but says he may be forced to withdraw from the tournament if the pain becomes too much.
The five-time world champion admitted after the game that he will not start Sunday's second-round match against Leeds veteran Peter Lines or Northern Ireland's Joe Swail if there is no improvement.
"The injury is disappointing, a broken ankle. It is not too comfortable and I didn't enjoy any of that," the 38-year-old said.
"I thought I would give it a go but if it doesn't improve I'm not sure I'm going to play my next match. I can't get on the shot properly, I'm hobbling around, it's swelling up and it's painful.
"I've taken all the painkillers, done all I can do, and if it's not better by Sunday I probably won't play."
He added: "I am absolutely gutted. I am enjoying my snooker more than ever and to do that through running - I am really angry with myself.
"I am so annoyed at myself. I think I will probably stop running now until the end of my snooker career because you can't do this.
"It's the third time I have broken my foot. I fell over in the forest. I was running with my mate and he'd asked me what time I was doing the run. I looked at my watch and I just lost my footing and I slipped.
"That was it. Partly his fault, partly my fault and I am frustrated with myself because I am a snooker player, not a runner. I just shouldn't do it. It is really frustrating."
O'Sullivan was not the only walking wounded at York, with two-time world champion Mark Williams beating Steven Hallworth 6-1 despite a muscle injury picked up during weight training. Jack Lisowski also won by that scoreline against Chris Melling.
Elsewhere, 1997 world winner Ken Doherty beat Mitchell Mann, Marco Fu avoided a shock loss to Ahmed Saif while Mark Davis, Liam Highfield, Luca Brecel, Robin Hull and Jimmy Robertson also progressed.