Michael Phelps displayed ice-cool composure as a record-breaking Olympic swimmer but he was a bag of nerves on Wednesday when he played the "noisiest hole in golf" in the pro-am competition for this week's Phoenix Open.
Phelps, who retired from swimming as the most decorated Olympian of all time after winning a record 22 medals including 18 gold, was paired with U.S. Masters champion Bubba Watson when he stepped on to the 16th tee at the TPC Scottsdale.
Hugely popular with the fans, the infamous par-three is a 162-yard hole widely regarded as the loudest in golf and is completely surrounded by massive grandstands where thousands of raucous spectators are crammed in to savor the action.
"I was very nervous and my club was like shaking as I'm over the ball," Phelps told reporters about his tee shot on 16. "I felt my heart was going to jump out of my chest.
"I just pretty much had to try to swing the club as fast as I could."
Phelps's tee shot landed on the green but rolled back off the front, sparking good-natured boos from rowdy spectators.
"But it's wild. I've never heard people boo you, but I'm sure it's happened before, my face is just under water," Phelps said. "So it was a little different experience.
"Hopefully I will have a chance to come back and play again. It's a great event. I had a blast today and being able to play with Bubba, that's something else. We were throwing jokes back and forth the whole entire time and keeping it very light."
Phelps has set his sights on becoming a top golfer and is the subject of the Golf Channel's 'Haney Project' which will be aired next month.
Swing guru Hank Haney, who helped former world number one Woods win 31 PGA Tour events and six major championships, has previously worked with former NBA All-Star Charles Barkley, actor Ray Romano and singer Adam Levine.
"I'm not saying I'm going to be on the tour, that's not it," Phelps told Reuters during last year's Ryder Cup about his golfing ambitions.
"I enjoy doing this, I enjoy being outside. I have a kind of a plaque with the top 50 courses and I'm just trying to mark every one of them off."
American left-hander Watson, who clinched his first major title in a playoff for last year's Masters after conjuring a miraculous shot from pine straw, was impressed by what he saw of Phelps's short game on Wednesday.
"It's one of those things where he's a great athlete, one of the best Olympians, or the best Olympian, coming to a different sport, so obviously it's a big change," Watson said.
"It's a different mental set, a different mental focus and he's not used to it. But you can see he's an athlete and he's competitive, so he could be good if he practiced and put some time into it."
The Phoenix Open, the fifth event on the 2013 PGA Tour schedule, starts on Thursday.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Ian Ransom)