The best season of Jason Day's career began at the Farmers Insurance Open when he won a four-man playoff, the first of his five victories that for a brief time took him to No. 1 in the world.

Before he can defend his title, however, Day has to get to the first tee.

The 28-year-old Australian pulled out of the pro-am Wednesday at Torrey Pines because of the flu. Still to be determined was whether he was fit enough to play.

Day said Torrey Pines is special to him because he came here for the Junior World Championship at age 16.

If he can play, it would be the first time Day is at a tournament that does not have either Jordan Spieth (playing in the Singapore Open) or Rory McIlroy (week off before he plays in Dubai). That won't make it any easier.

Rickie Fowler is coming off a victory in Abu Dhabi, his fourth title worldwide in the last eight months that took him to a career-best No. 4 in the world. Also in the field is Dustin Johnson, Patrick Reed and the hometown favorite, Phil Mickelson.

Here's how the opening round is shaping up Thursday at Torrey Pines:

WHAT WILL PHIL DO NEXT?: Mickelson has a love-hate relationship with Torrey Pines, which he knows better than anyone in the field from growing up in San Diego and entering his 25th year on the PGA Tour.

He loves Torrey Pines because it's home and he won here three times. He's not so fond of the work Rees Jones did to the South Course to prepare for the 2008 U.S. Open. Mickelson hasn't won in 15 years.

And even the North Course brings back not-so-fond memories. Mickelson was supposed to redesign the course and had grandiose plans to bring the gorgeous canyons into view, only for the California Fair Political Practices commission to rule that anyone involved in the design of a project cannot follow through on the work.

"It's certainly disappointing for me, but I understand the politics of it all," he said Wednesday. "Actually, I don't understand the politics of it all. It makes no sense."

As for his game? He has a new coach, and began the season with a tie for third last week at the CareerBuilder Challenge. Torrey will present a stiffer test.

HAVE GAME, WILL TRAVEL: Spieth said he was tired after his tie for fifth last week in Abu Dhabi, having played twice in Asia, once in Australia, once in the Bahamas, once in Hawaii and once in the Middle East in the last four months.

Imagine how Fowler feels.

Even though he grew up an hour away, he traveled the farthest to get here. Fowler left Abu Dhabi after his victory Sunday and arrived Monday morning in San Diego in time to host a junior clinic. He says he can't wait to play again, which is Thursday. And winning tends to negate fatigue.

AUSSIE DEBUT: The PGA Tour debut of 17-year-old Ryan Ruffels just got a lot more interesting.

The Aussie teen told a tale to the Sydney Morning Herald about playing with Mickelson at Torrey Pines last month and winning $5,000 off of him. Two days later, Ruffels said the story wasn't accurate. He wanted to point out that no NCAA rules were violated (he was an amateur playing with Mickelson and his brother, Arizona State golf coach Tim Mickelson) and that the amount was "out of proportion."

Mickelson didn't take too kindly to it all.

"He's young, and he's got some things to learn," Mickelson said. "One of them is you don't discuss certain things. You don't discuss specifics of what you play for. And you certainly don't embellish and create a false amount just for your own benefit. So those things right there are ... that's high school stuff."

ROSE BEGINS: Justin Rose is the highest-ranked player at No. 7 in the world to have not played this year.

That changes Thursday.

Rose last played at the Hero World Challenge on Dec. 6 and he closed with a 62. That's a nice way to go into his winter hibernation.

"I wait until I get that itch to play again," he said. "I think it's really important to miss the game of golf."