Mark Williams shrugged off a bout of gout to progress at the Coral World Grand Prix in Cheltenham with a 4-2 victory over Barry Hawkins.
The three-time world champion wore a slipper on his left foot and was in obvious pain as he limped around the table to play his shots.
But the 44-year-old Welshman still overpowered former Grand Prix champion Hawkins to book a second-round clash with Neil Robertson.
"I've never had gout before," Williams told ITV 4.
"I've heard people say how painful it is and now I know, it's unbelievable.
"You can't get a sock on it. You're lying in bed and can't even have the bed sheets touch you.
"You're screaming in pain and you can't do anything about it."
Gout is a form of arthritis caused by excess uric acid in the bloodstream.
The severe joint pain, which can be treated with medication, is often associated with alcohol and bad diet.
But Williams said: "In the last month I've ate so healthy, I haven't had one drink and no fried food.
"I've been eating pasta and jacket potatoes. I've been walking 30 miles a week playing golf and I get gout.
"So I'm just going to have a kebab tonight and get back on the Budweiser!"
In other first-round action, John Higgins beat Stuart Bingham 4-2 for a sixth successive win over the Masters champion.
Higgins' second-round opponent will be Zhao Xintong, who overcame fellow Chinese Yan Bingtao 4-2.
Kyren Wilson beat Jack Lisowski 4-3 in a nerve-jangler.