The world No 3, due to meet Alan McManus or Dennis Taylor tomorrow, tripped and fell, sustaining the injury. However, O'Sullivan, who has already missed two events this year because of health problems, insists he will be able to compete in the best-of-nine frame quarter-final at Derby's Assembly Rooms.
"It's not as bad as I'd feared and it will heal itself with time," said the 23-year-old. "I was in a hurry and I fell on the finger. I was worried I wouldn't be able to play but I took a few pain-killers and I'm OK now. It was just a stupid thing that happened. It certainly stops me playing left-handed, which I've been doing lately."
O'Sullivan is a former winner of the Charity Challenge title and finished runner-up in 1996 when Stephen Hendry made a 147 break in the deciding frame.
On the table yesterday, Steve Davis became the first winner in the 1999 event, beating Peter Ebdon 5-3. Davis now meets John Higgins, the world champion and world No 1, for a place in the semi-finals of the event.
"It's nice to bounce back after playing so badly in Scotland last week," said the 41-year-old six-times former world champion, who lost in the first round in Aberdeen against Darren Clarke.Reuse content