Five-time world champion Raymond van Barneveld is being monitored by medics after collapsing at the Players Championship 8 on Friday.
The Dutchman, 53, required medical assistance after becoming unwell soon after his first-round defeat at the event in Milton Keynes.
He was seen to by paramedics but did not require hospital treatment and has returned to his hotel to be monitored.
Play was suspended while he was treated before resuming at 14:45 GMT.
Van Barneveld was beaten 6-1 by England's Ryan Searle earlier on Friday.