Who are these guys leading the Open?

The first-round leaderboard at the $5.1 million Canadian Open at St. George’s Golf and Country Club is a “Who’s Not Who” of the professional golf world.

Brent Delahoussaye, a struggling rookie from Greensville, S.C., who quite frankly no one covering this tournament had ever heard of destroyed the 7,046-yard layout, with a blistering eight-under-par 62. His shocking round now stands as both a competitive course and Open record. Tied for second, only two strokes back were Brock Mackenzie and Vance Veazey — who like Delahoussaye have never won a PGA tournament. Never even had a sniff. Veazey and Mackenzie matched the previous course record, held by Canadian legend George Knudson — with six-under par 64s

Nine golfers finished at 65, most of them unfamiliar to golf fans as well, the exception being Hunter Mahan. “I’m shocked. I knew I was playing well, and I didn’t even know how many under I was at one point,” said Delahoussaye, who played his historic round with a pair of Canadians — Jon Mills of Oshawa and Moose Jaw’s Adam Hadwin. “I’ve played with Jon a bunch on the Nationwide Tour. All three of us played pretty well. The crowd was really great for all of us. I know they’re both Canadians, but they were really good to me. We just had a good time.” Mills shot a three-under par 67, tying him with Calgary’s Stephen Ames for the lead among Canadians. Hadwin finished at 68.

Delahoussaye, 29, was one of the last golfers to tee off Thursday on a course many predicted would offer stiff resistance. So much for that thought. “I woke up this morning and looked and the scores and said: ‘Wow!’ I did not see that many low scores out there in the practice round (on Tuesday).”  Delahoussaye, whose best finish on the PGA Tour was a tie for 53rd in the Byron Nelson, eagled his first hole, the par-5 ninth, birdied the 10th and never looked back. “I wasn’t thinking about a course record,” he continued. “Or thinking about leading the tournament. I was just thinking about hitting shots, and I just need to take that mentality into the next three days.”

Rain is in the forecast for Friday’s second round. “I imagine it’ll be tougher,” said Delahoussaye, who had one eagle, six birdies and a bogey during his round. “I know there’s three days of golf left on a tough course, and I’m just going to go out there and play one shot at a time like I did today.”  Delayoussaye said he didn’t do anything special in the 24 hours leading up the tournament. “My wife and I went to the Bon Jovi concert (at the Air Canada Centre). I woke up the same way I always do. I put on my pants the same way I do every morning. With a 2:15 tee time I didn’t even have to set the alarm.”

Mackenzie, from Coos Bay, Ore., has only played one other PGA tournament this year and missed the cut. He got into the tournament based on his recent success on the Canadian Tour. “One shot at a time,” Mackenzie said when asked about his thoughts for Friday’s second round. “My game felt good today but I also know I can sleep wrong and feel totally different tomorrow. “Hopefully, it’s the same way the next three days.”