(CNN) -- Roberto Castro enjoyed an impressive debut at the Players Championship, carding a nine-under-par round of 63 to tie the course record at TPC Sawgrass and top the leaderboard after day one of the $9.5 million tournament.
Yet to record a PGA Tour win in his six-year career, the American equaled the record set by golf icons Fred Couples and Greg Norman to lead two-time major winner Rory McIlroy and 2007 Masters champion Zach Johnson by three shots.
"Tiger Woods (didn't) play till this afternoon," Castro told the Tour's official website after a round which included seven birdies and an eagle at the second hole. "So I'm sure some people were looking for something interesting to watch.
"The last two weeks I've hit the ball nicely, the scores just haven't shown it. A couple of rounds, especially in the last two weeks, could have been low. They weren't even remotely low on the scorecard, but had a couple of quality shots."
Playing alongside Castro was compatriot Jason Bohn, who suggested the 27-year-old's round could have been even better.
"It was a clinic," said Bohn, who was four under at the end of Thursday's play. "It was beautiful. I've never seen a 63 shot like that.
"You see guys chip in or hole a bunker shot; but he shot 63 and it could've been two or three shots lower."
McIlroy enjoyed his best ever day at the event, having missed the cut and failed to break par on his three previous trips to Ponte Vedra Beach.
The world No. 2 was part of a stellar threesome which also included recently crowned Masters champion Adam Scott -- playing for the first time since his Augusta triumph -- and 12-time PGA winner Steve Stricker.
"I think when you get all three guys playing well in a group, you sort of feed off one another," said McIlroy. "It was a good group to be a part of."
Scott, who won the Players in 2004, was satisfied with his opening round of 69.
"I was a little surprised when I teed off that someone was five under already," explained the Australian. "I thought it might play a little tougher than that. But it was ideal.
"There wasn't even a breath of wind hardly on the front nine. The greens seemed pretty receptive, too, so if you were in the fairway you could attack."
A slip up at the 18th dashed world No. 1 Tiger Woods' hopes of carding a first bogey-free round at the Players.
The 14-time major winner carded six birdies during his round of 67, one stroke off his career best score at the event.
"I felt like I hit the ball good enough, but more importantly, I missed the ball in all the correct spots," said Woods, who is looking to win the tournament for the second time.
"I left myself some easy up and downs, and I was able to convert those up and downs."