SAN FRANCISCO (AP) Rory McIlroy arrived at Harding Park on Monday knowing he will be at the Match Play Championship at least through Friday.
So will the rest of the 64-man field.
In a format change to avoid the single elimination that often sent the stars home early, the Cadillac Match Play Championship features 16 groups of four players, with the best record from each group advancing to the weekend.
And there was one other twist - the groups were decided by a lottery.
Golf balls gave way to pingpong balls that were plucked out of a bowl to determine which players went into each of the 16 groups. The balls had numbers corresponding to the seeds (based on the world ranking), with Nos. 1-16 serving as the top guy in each group and the other players broken down into sections of Nos. 17 to 32, Nos. 33 to 48, and Nos. 49 to 64.
Had it been a straight draw, top-seeded Rory McIlroy would have been joined by Graeme McDowell (32), Keegan Bradley (33) and Francesco Molinari (64). With the lottery system, McIlroy got Billy Horschel (18), Brandt Snedeker (35) and Jason Dufner (53).
Masters champion Jordan Spieth, the No. 2 seed, drew Lee Westwood (26), Matt Every (40) and Mikko Ilonen (62).
One thing hasn't changed. For all the analysis of who had the toughest group, match play remains as unpredictable as ever.
''It's a tough road to get to Saturday,'' Snedeker said.
The other change, of course, is the venue. Harding Park is a tight, tree-lined public course in San Francisco that hosted the 2009 Presidents Cup and a World Golf Championship in 2005. It's nothing like Dove Mountain in the high desert of Arizona, a wide-open course at altitude that favored power and was toward the bottom of just about every player's list of favorite courses.
Tiger Woods was the star both times the best in golf came to Harding Park. He beat John Daly in a playoff at the American Express Championship, and he went 5-0 in the Presidents Cup. Woods failed to qualify for the Match Play for the first time since it began in 1999. He now is No. 116 in the world.
Phil Mickelson also was a late scratch for what he described only as ''personal reasons.'' This marks the fourth straight year that Mickelson has missed the Match Play, where he has reached the quarterfinals only once.
Monday was a light day of practice, and there was a rare pro-am for a WGC event before the tournament begins on Wednesday.
There will be no halved matches during round-robin play. Tiebreakers will be determined by head-to-head matches, and in case of a three-way tie in a group, there will be a sudden-death playoff to see who advances.
The round of 16 on Saturday morning will be followed by the quarterfinals in the afternoon, and then the semifinals and championship match on Sunday.
Most players embraced the change, and it certainly helps with the sponsor and the public. No more than five of the top 10 seeds were around by Friday in the last three years of single elimination.
''Just because you have a bad nine holes doesn't mean you're going home until the weekend. That's a comforting fact,'' Snedeker said. ''But you still have to play great golf. I think everyone is excited about the fact there's no way to fake it. The guy playing the best is going to get out of his group.''
No one was happier than Ilonen, who only got into the field when Mickelson withdrew. Ilonen played in the Volvo China Open on Sunday, flew over to San Francisco as the first alternate and was prepared to wait around for two days and fly home to Finland if no one withdrew.
When he landed in San Francisco on Sunday night, he had a text from his wife that he was in the Match Play.
''I said, `How do you know?' She told me she saw it on a website,'' Ilonen said.
He didn't trust what he heard until he went to a higher authority - Twitter.
Walking through the dining room, he quickly went over to his first-round opponent to greet him. That would be Spieth, and the sole purpose was to congratulate the 21-year-old Texan for his wire-to-wire Masters victory.
There is a different buzz to the new Match Play. San Francisco is a refreshing change from Marana, Arizona, for one thing. And there was less a sense of urgency about the Wednesday matches. Everyone is guaranteed three cracks.
''And then it will start feeling like the old one,'' Jimmy Walker said. ''But it's still match play. You're still trying to beat the other guy. You've got to play good.''