Rory McIlroy is braced for a "crazy" second round of the US PGA Championship after experiencing a bout of Tiger-mania in St Louis.
The marquee group of McIlroy, Tiger Woods and defending champion Justin Thomas drew massive galleries for an 0823 tee time on Thursday morning at Bellerive Country Club.
And the crowd is likely to be even bigger when the star trio begin their second rounds shortly before 2pm on Friday afternoon, with Thomas one under par and Woods and McIlroy both level par.
"It was pretty cool to be out there 8:30 in the morning and have an atmosphere like that," McIlroy said. "JT and I were saying it's going to get a little crazy tomorrow afternoon. So we're looking forward to that.
"Harry [Diamond] caddied for me in the 2005 Irish Open when I was 16 and then we're walking the fairways in a group like this today, 13 years later. So it's pretty cool."
McIlroy wore an anti-inflammatory patch on his right arm as he compiled an opening 70 which featured two birdies and two bogeys on the outward half and nine pars in a row to finish.
"I started feeling it the weekend of Firestone," the 29-year-old said. "It hurts the most with chipping because I sort of hold the angle a little bit. The whole forearm has been tight.
"I hit a lot of balls last week at Firestone working on a few things and it's just a little inflamed and a little tight, but it's fine.
"I wish I could have taken advantage of the two par fives. I gave myself a few chances and it could have been a little better.
"I feel like I hit good putts out there today. They either didn't want to break or they hit something so it was tough. You just had to stay patient."