If he had it do over again, U.S. Open champion Rory McIlroy would not have picked a fight with a tree root.

"It was a mistake in judgment," he said.

McIlroy walked away from the mishap with a strained tendon, but it wasn't enough to keep him from resuming the PGA Championship — despite some soreness Friday morning in his right wrist. And even though he is eight shots off the lead at Atlanta Athletic Club, the 22-year-old from Northern Ireland has not ruled out winning.

"If I don't think I could contend, I probably wouldn't be playing," he said.

Told that he could do no further damage, McIlroy had his wrist heavily taped, had Titleist ship him a new 7-iron that was broken in the battle with the root on the third hole Thursday, then went out and shot 3-over 73.

The problem was not so much the wrist as it was the par-3 17th.

McIlroy swirled in a 45-foot birdie putt on the previous hole to get to 1 under for the tournament, enough for fans to yell out his name as he headed the 207-yard par 3 over water. He had a 7-iron, then switched to a 6-iron and hit it a bit higher than he wanted.

He was shocked when it came down short of the green, and looked over at caddie J.P. Fitzgerald and mouthed, "Wet?" Worse yet was a three-putt that followed when he did get to the green, giving him a triple bogey and killing his momentum.

"It was tough to come back from that," McIlroy said.

Still, the big part of his day was getting to the golf course. McIlroy had an MRI on his wrist Thursday night that showed not even a partial tear. The "Rory Watch" on the practice range began an hour before his 8:30 a.m. tee time, and just the kid showing up in a cart 30 minutes later caused a minor buzz. He hit balls for 15 minutes, then headed toward the putting green.

"If it wasn't a major, I probably would have stopped yesterday," McIlroy said. "To be honest, looking at the scans, they said, 'Look, you can't do any more damage to it, it's up to yourself. If you want to play and you feel as though you can play OK and carry on, then do. And if not, then you shouldn't play.'

"I feel as if I can play, so the decision was purely up to me."

It's always up to Rory, and he made that clear when someone questioned whether his caddie — at the center of a Twitter debate two weeks ago involving a BBC commentator — should have talked him out of hitting a ball that was up against a 2-inch wide root Thursday.

"He's my caddie, not my father," McIlroy said.

Chubby Chandler, his agent at International Sports Management, said McIlroy is his own man in many areas. It was McIlroy's decision two years ago to play the PGA Tour, and his decision to rejoin for next year. The only debate about the debate "root shot" was the degree of difficulty.

"I didn't see it. I only saw the replay. But he told he it was this far away, and it was that far away," said Chandler, holding his hands about 3 feet apart, then narrowing them to within inches.

"There's not a chance J.P. will ever be able to influence anything he's doing," Chandler said. "And I can't, either."

McIlroy was bothered more by his putting than anything else after the second round. He missed birdie chances on three straight holes before converting the long one at the 16th. He three-putted a par 5 on the front nine. His other bogey came at the third, when he tried to blast a shot out of the soft sand and watched it roll back into the bunker.

McIlroy said the strength of his wrist is probably at 75 percent.

"I'm worried about it because I feel as if I can't play to the best of my abilities with it," he said. "But I'm not worried about it long term. It should take a few weeks just to heal."

In the meantime, he has two days to make up a big deficit.