World number two Jason Day is a doubt for the defence of his Farmers Insurance Open title at Torrey Pines after being laid low by a virus.
Day pulled out of the pre-tournament pro-am but hopes to be fit enough on Thursday to play the opening round of the £4.5million event, one of the five tournaments he won in 2015.
The good news for fans of the 27-year-old US PGA champion is that the last time he missed a pro-am, he went on to shoot 61 in the opening round of the Barclays and win for the third time in four starts.
If Day does miss out, the event can still boast an impressive field, with new world number four Rickie Fowler making the 17-hour journey from Abu Dhabi after winning his second European Tour title on Sunday.
Dustin Johnson, Phil Mickelson and Justin Rose are also competing, while Irishman Paul Dunne makes his PGA Tour debut on a sponsor’s invite.
Dunne hit the headlines last summer when he became the first amateur since 1927 to share the lead of the Open Championship after 54 holes, before eventually finishing 30th at St Andrews.
The 23-year-old went on to gain his European Tour card via the qualifying school in November but is taking advantage of a gap in his schedule to play in the United States, where he attended the same college as former US Open champion Graeme McDowell.
Paul Dunne and Shane Lowry will both feature on the @PGATOUR this week at the Farmers Insurance Open— Just Golf (@JustGolfIE) January 26, 2016
“I’m very excited to make my PGA Tour debut this week and spend a few weeks in California,” Dunne, who turned professional after helping Great Britain and Ireland to a record Walker Cup win, told a pre-tournament press conference.
“When I was playing in college I was always striving to turn pro and play golf on a professional tour and I was excited to get my European Tour card back in November. And now I have a few weeks off the European Tour I’m really excited to see what the PGA Tour has to offer.
“Category 16 status on the European Tour is for Q-School graduates, so it doesn’t get you in every event. When I was looking at the schedule I knew I had the first couple of events in South Africa (he finished ninth in the Joburg Open) and then my category wouldn’t get me into the events in the desert swing.
“So I knew I had a good break in tournaments and then we just sought places to play and looked to America. We were lucky enough to get invites over here.
“Obviously the overall goal for me would be to end up on the PGA Tour so any exposure I can get to that early is great.
“In terms of goals for the week, I kind of set my goals at the start of the year to just try and improve every day. Get better each week and let results take care of themselves. So I’m just going to keep working on my game and hopefully I put some good scores together.”