London - Masters champion Danny Willett confirmed on Friday a back injury has forced him to pull out of the World Cup of Golf in Melbourne, where he was due to represent England alongside Lee Westwood.
Willett, 29, missed the British Masters last month due to an ongoing back problem and said he did not want to risk aggravating the problem by competing at Kingston Heath.
"I was really looking forward to playing the World Cup with Lee Westwood, but considering everything, including the amount of travel involved and extra strain, decided that it was not in my best interests," Willett said in a statement.
The World Cup, from November 24-27, would have been the fifth tournament in succession for Willett, who was 75th in the WGC-HSBC Champions and 68th in the Turkish Airlines Open, both events having just 78 players.
Willett is currently in a tie for 54th in the 72-man field at the Nedbank Golf Challenge in South Africa and will need a good performance in the season-ending DP World Tour Championship in Dubai next week to overhaul Race to Dubai leader Henrik Stenson.
Twenty-eight two-man teams representing their countries will contest the World Cup, which this year returns to a 72-hole, stroke-play event format.
The first and third days of competition will be the foursomes format and the second and final days are fourball play.