Shane Lowry and Rory McIlroy laughed together at dinner Tuesday night, about 18 hours before their scheduled first-round WGC-Accenture Match Play Championship contest.
Lowry had the ribs at Lil Abner's Steak House.
He and his childhood friend - who happened to also be the world's No. 1 golfer - cheered together when, at their table of nine, two caddies lost Credit Card Roulette and had to pick up the tab.
"It's only a game of golf," Lowry said. "It's not life or death. We're not going into battle."
One day and a snow cancellation later, the vibe between the two changed during Lowry's 1-up upset of the tournament's top seed Thursday at The Golf Club at Dove Mountain.
Their chummy chatter wore off after a few holes.
"I tried to keep it that way," said the 25-year-old Irishman, who has already eclipsed his top PGA Tour showing, when he tied for 37th at the 2010 British Open. "I said to my caddie walking down 11 or 12, 'He's not liking this one bit.'
"He's the one under pressure. I've got nothing to lose, so let's have a go from here.' I just tried to focus on my game."
Focus? The No. 64 overall seed holed out at 11 on an 18 1/2-foot chip.
On the next hole, he did it again, from the base of a tent 35 feet 3 inches from the cup. He flipped the ball to a fan in the crowd.
"The crowd always likes the underdog, don't they?" Lowry said. "I got a few cheers toward the end - more than I got on the first few holes.
"Those chip-ins and 11 and 12 were massive, and they gave me the momentum to go on and win the match."
Lowry halved 11 and won 12, the latter coming when McIlroy sat 3 feet 10 inches from the cup.
"The momentum shifted a little bit," said McIlroy, whose second tournament using new Nike clubs ended no better than his first, when the Northern Irishman missed the cut in Abu Dhabi.
Neither claimed to play exceptionally; McIlroy even said he "probably would have lost by more if I had played someone else in the field," and that "it wasn't a great quality match."
But Lowry made impressive, if not flashy, iron shots, on the last two holes.
On 17, he stuck a chip within 2 1/2 feet of the cup to halve the hole.
And on 18, with McIlroy needing a win to force extra holes, Lowry landed in the same sand trap to the right of the hole as the world's No. 1.
From the green-side bunker, McIlroy chipped within 3 inches of the hole.
From 44 feet, Lowry put the ball within 3 feet 11 inches of the cup, and made the putt to halve the hole and win the match.
"It's probably better than I imagined the other day," he said. "It's a great feeling.
"But at the end of the day, as I said, it's only the first round.
"I've not conquered and done it yet. I've only beaten one player, and I'm here to beat more."
Lowry said the pressure "was a bit of a banana skin" for McIlroy.
"It's a bigger win for me than it would have been for him," he said.
Lowry, who plays the winner of the delayed Rickie Fowler-Carl Pettersson match at 11:44 a.m. today, said he was more comfortable playing his old Irish amateur teammate than any other top seed because "I just know Rory so well."
"I'm sure, after a few weeks or a couple of months, I will slag Rory over it," he said. "But at the end of the day, it's only the first round.
"I've got a match tomorrow I need to focus on."
Contact reporter Patrick Finley at firstname.lastname@example.org or 573-4145. On Twitter @PatrickFinley