HOUSTON — Ernie Els withdrew from the Houston Open today because of a virus, giving him an unexpected two weeks off before going to the Masters.

"I am very disappointed to have been forced to make this decision because I was really looking forward to playing this week," Els said in a statement. "The Shell Houston Open was going to be an important part of my buildup toward the Masters, but I have been advised that it would not be in my best interests to play."

Els said it was a similar virus to the one that caused him to arrive late at the CA Championship at Doral, where he failed to break par all four rounds and finished at the bottom of the pack.

He had planned to play five out of six weeks on the PGA Tour to prepare for the Masters, but will wind up playing only three times. He won the Honda Classic at the start of the Florida swing for his first U.S. victory in 3½ years, missed the cut the following week at Innisbrook, then pulled out of the Arnold Palmer Invitational, citing fatigue.