World No 1 and defending champion Rory McIlroy withdrew from the US PGA Honda Classic during his second round on Friday, saying he was struggling due to pain from a sore wisdom tooth.

McIlroy struggled through the back nine, his opening nine holes of the round, and hit his approach at the 18th into water. He then walked off the course and quickly departed the grounds with his coach and caddie.

"I sincerely apologize to The Honda Classic and PGA Tour for my sudden withdrawal," McIlroy said. "I have been suffering with a sore wisdom tooth, which is due to come out in the near future."

It was the first time in his career that McIlroy has withdrawn from a tournament and it comes as the 23-year-old from Northern Ireland struggles to find his form after switching to Nike equipment this season.

McIlroy is a 6-1 co-favorite with 14-time major champion Tiger Woods in next month's Masters, but the tooth issue could dim his bid to add to a major haul that includes the 2011 US Open and 2012 PGA Championship.

AFP