Daly was due to play with Lee Westwood and Henrik Stenson

The 40-year-old former Open and USPGA champion, who won this event in 2001, withdrew before start of play after failing to recover from the illness.

His place in the competition has been taken by England's Robert Rock.

Meanwhile, Fred Couples has pulled out of next week's Singapore Open with what is believed to be the same viral illness that has affected Lee Westwood.

Westwood, who stayed in the same hotel as Couples last week, was forced to withdraw before the start of the final round of the WGC-Bridgestone Invitational in Akron, Ohio, last weekend.

The 33-year-old Englishman, who cannot qualify automatically for the Ryder Cup, is playing in Germany this week in order to catch the eye of European skipper Ian Woosnam - who has yet to name his wildcard picks.

The BMW International Open is the final event before the European team is selected. The Ryder Cup starts at the K Club, County Kildare, on 22 September.

Daly was ill on his arrival in Germany on Tuesday and pulled out of a shootout that day as well as Wednesday's pro-am.