This is one week where Jason Day is not trying to make friends.

The Match Play Championship brings out an edge in the 27-year-old Australian, who doesn't lack for confidence in any format and yet seems to crank it up a notch when he only has to worry about the guy he's playing.

It worked well for Day a year ago in Arizona when he never trailed over the final 53 holes and outlasted Victor Dubuisson to capture his first World Golf Championship.

"I really want to have a great record here and let everyone know that I'm one of the best match play players in the world," Day said. "If you play me in match play, you're going to have a tough time."

Those were strong words at a time when the focus is on the top two players in the world — Rory McIlroy and Masters champion Jordan Spieth — and there are plenty of others in the Cadillac Match Play who have strong reputations in this format. Ian Poulter has won 22 matches, the most of any player in the field. Matt Kuchar, Hunter Mahan and Henrik Stenson are among past champions in the field at Harding Park.

Day is as pleasant as they come in a sport that is congenial by nature. He's just a different person in match play.

He recalled a match two years ago against Russell Henley when Day didn't concede a couple of putts in the 2-foot range. It's a common practice in match play to concede putts, depending on the circumstances. Henley is noted for his pure putting.

"He turned around and he was getting angry," Day said. "I could tell that he was kind of getting a little (ticked) at me."

That turned out to be mistake. Day said he learned in that match that Henley plays well when he's burning, and Day had to go 19 holes to beat him.

In his Match Play debut in 2011, Day beat Paul Casey on the 16th hole and recalled another episode of not conceding putts and Casey not being terribly happy about it.

"I made him putt in like a foot putt. It was really small," Day said. "And then he got up and stared at me. I could sense it that he was staring at me because it was like he was burning a laser through me from the side. And then he ended up losing the next two holes and I won."

It's nothing personal for Day. He expects to have to hole every putt, and he feels his opponent should expect to do the same.

"It's amazing how many times I've walked off the golf course thinking, 'Man, that guy doesn't like me anymore,'" Day said with a laugh.

A similar question was posted to Poulter. Has he ever detected that he was annoying an opponent?

It was a loaded question.

"Plenty. Plenty," Poulter said.

More than not conceding putts, Poulter chalked it up to being stubborn — a good trait in match play — and relentless.

"I think that's probably the hardest bit for people to take when you think you're out of the hole and all of a sudden you go and hole a chip shot or a bunker shot or a 30-foot putt, or you stiff it from a position where you're not expected to hit a miracle shot," Poulter said. "I guess that in itself is the bit that winds your opponents up."

All the fun starts again Wednesday with a new format, a new golf course and even 11 new players to the most fickle tournament in golf.

The biggest change is golf course, going from the high desert of Dove Mountain in Arizona to the heavy, cool Pacific air of Harding Park in San Francisco. That would seem to eliminate an advantage for the big hitters who thrived on power and altitude.

Then again, match play is not easily explained.

"We've seen short par 4s and short par 5s messed up by big hitters," Poulter said. "And yes, they might have an advantage in length over me on those holes. But match play is match play. There are ways to win and lose holes. And you really are playing your opponents."

The format change means that everyone has three opponents, at least until the weekend.

There are 16 groups of four players, with a round-robin format through Friday and the winner of each group advancing to the round of 16 on Saturday morning. That could be good news for someone like Poulter, who played poorly in his opening round last year and lost to Rickie Fowler, who didn't play much better. It's also helpful to 12 players who have never made it out of the opening round, a group that includes Jamie Donaldson (0-2) and Gary Woodland (0-2).

"Back when we played in Arizona, you could play a really good round of golf and match play is bit of a lottery," McIlroy said. "You can get a guy that's got really hot and you play better than 85 to 90 percent of the field and you're going home. It's just the way it is. I feel like this gives players a better chance to progress, and if they are playing well, it seems like a bit of a fairer format."

For all the changes, however, one element remains.

"All in all, you're playing that guy across from you," Spieth said.

And if that guy happens to be Day, don't expect to hear the words, "Pick it up."