Bubba Watson has withdrawn from this week's Farmers Insurance Open at Torrey Pines in San Diego due to illness.
Watson made a winning birdie at the par five 18th to win this event two years ago and was joint-third favourite at 14/1 to triumph again this week.
But, shortly before the tournament began on Thursday morning, he tweeted: "Pulling out of tourney this morning, don't have energy for golf. Feel the same as Maui."
Watson had a stomach illness during the season-opening Tournament of Champions on the Hawaiian island of Maui although he battled on to tie for fourth.
The Masters champion added in a follow-up tweet: "Wife and I are sick, hope little man (their son) doesn't get it. Time to rest and be ready to play next week."
The big-hitting left-hander was due to play with three-time Farmers Insurance Open winner Phil Mickelson and defending champion Brandt Snedeker.
He was replaced in the field by Billy Mayfair.
If recovered, Watson's next start will be the Waste Management Phoenix Open in Arizona.