ANCASTER, Ontario (AP) — Scott Piercy kept his cool in the rainy first round of the Canadian Open.

Instead of beating up himself, the quick-tempered American roughed up defenseless Hamilton Golf and Country Club, shooting an 8-under 62 on Thursday to take a one-shot lead.

"I get really mad generally," Piercy said. "That's something that I have to very much control. And it's a lot easier to control when you're playing well. ... It's something that I constantly have to work on. I'm kind of a perfectionist in an imperfect game. ... It's just a constant battle within me that I always have to kind of keep it nice and chilled. Golf is the only time I get really upset."

Piercy eagled the par-5 fourth and 17th holes and had five birdies and one bogey in the rainy conditions to match the competitive course record set by Warren Sye in the third round of the 1991 Ontario Amateur. The 33-year-old Las Vegas player is coming off a third-place finish two weeks ago in the John Deere Classic.

"Hit a lot of fairways and a lot of greens today," Piercy said. "I was rolling the ball well, and obviously you got to make some putts, too. Hit it solid out there. I think I only missed a couple greens, and ball-striking around here with the rough being so penal is a must to shoot well."

He birdied three of his final five holes, punctuated with a 10-foot putt on No. 9.

"The greens were receptive," Piercy said. "I wouldn't say overly soft or hard."

Greg Owen and William McGirt shot 63, and Robert Garrigus had a 64. Charl Schwartzel, the 2011 Masters winner, was at 65 along with 2004 Canadian Open champion Vijay Singh, Troy Matteson, Bo Van Pelt, Jhonattan Vegas, Stuart Appleby and Gavin Coles.

Ernie Els, the British Open winner Sunday at Royal Lytham & St. Annes, opened with a 72.

The course was a soggy mess by the end of the rainy day. Players were allowed to lift, clean and place their golf balls on the fairways, and 94 finished at par or better.

"I woke up this morning, I thought the British Open was a week early, looking out the window," Schwartzel said.

Jim Furyk, the winner in 2006 at Hamilton and 2007 at Angus Glen, shot a 70.

Adam Hadwin topped the 23 Canadians in the field, shooting a 66. The 24-year-old player from Abbotsford, British Columbia, tied for fourth last year at Shaughnessy in Vancouver.

"It seems every time we hit the end of July, I kind of springboard my game back into shape," Hadwin said. "I shot 4 under and I was 1 over on the par 5s today. So that's pretty good confidence going into tomorrow knowing that if I play those par 5s pretty well I'm going to play pretty well."

Slumping Canadian star Mike Weir was tied for 112th after a 72. He's trying to make his first PGA Tour cut of the year.

Pat Fletcher, born in England, was the last Canadian winner, taking the 1954 event at Point Grey in Vancouver. Carl Keffer is the only Canadian-born champion, winning in 1909 and 1914. Albert Murray, a Canadian also born in England, won in 1908 and 1913.

DIVOTS: Piercy has broken 70 in nine consecutive rounds. ... Owen is bidding to become the first Englishman to win the event since Peter Oosterhuis in 1981. ... George McNeill withdrew after shooting a 75, citing a back injury. ... Despite the rain, there was only one delay, lasting 20 minutes. ... John Daly shot 69. ... Hunter Mahan, a two-time winner this year, opened with a 70.