Former world champion Andy Fordham is expected to remain in hospital "for a few more days" after being taken ill at the Lakeside World Championship.
Fordham has suffered from health problems
Fordham forfeited his first-round match against Australia's Simon Whitlock after suffering breathing difficulties.
He was taken to an ambulance on a stretcher and his condition was described as "stable" on Tuesday.
"Andy has fluid on his right lung and it will be drained," said British Darts Organisation spokesman Robert Holmes.
There were fears initially that the problem was related to Fordham's heart, but he actually has a severe chest infection.
In November 2004, the 26-stone Fordham suffered an asthma attack during a break in his 'unification' clash with PDC champion Phil Taylor and had to pull out when losing 5-2.
Fordham lost four stone in weight after appearing on television programme "Celebrity Fit Club" but the commercial commitments he undertook after his World Championship win affected his form.
Whitlock, who beat Fordham 3-0 in the first round last year, will now face Niels de Ruiter in the second round but the 37-year-old was more concerned with the welfare of Fordham.
"I hope Andy is OK. Olly Croft (of the British Darts Organisation) came up to me half an hour before the match and said Andy wasn't fit to play, that he was having trouble breathing," he said.
"I was really looking forward to the match. I've been up since 2.30am and haven't had any sleep since then, just preparing to play.
"Obviously I'm a little disappointed that it's off because I've a lot of friends over here supporting me.
"But as long as Andy is okay, that's the main thing."
In the first of Monday's matches, former champion John Walton, seeded 14, had a hard-fought 3-2 win over Denmark's Brian Sorensen.
Walton admitted the short notice of the match being brought forward had not been ideal, but he fully understood considering the circumstances.
"I was told half an hour before we went on stage to get ready to go on first, which isn't easy when you've set your stall out for a different time," said the 45-year-old.
"But Andy's well-being comes before anything. All the best wishes go to him from everyone at the Lakeside."
Dutchman Niels de Ruiter, seeded 11, beat Brian Woods 3-0, and 15th seed Paul Hanvidge of Scotland beat Martin Phillips 3-2.