'The first round you never want to shoot yourself out of the game,' said the 42-year-old South African, who has won 10 titles on the PGA Tour and another 12 around the world. 'It's nice coming out shooting 65 this morning.'
Australia's Peter Lonard, a first-year PGA Tour player who has yet to miss a cut in 19 starts this season, posted a 5-under 66 for a share of second place with Byron Nelson Classic winner Shigeki Maruyama of Japan, Scott Gump and Hank Kuehne.
Steve Lowery, the runner-up here last year at Northview Golf & Country Club, was part of a 10-way tie for sixth place at 4-under 67. Lowery, who has top-10 results in his last five starts, including second-place showings at the Greater Milwaukee Open and The International, finished alongside WGC-Match Play champion Kevin Sutherland, David Gossett, Esteban Toledo and Tommy Tolles.
Tolles looked as if he would be the one leading after round one when he stormed out of the gate with five birdies and an eagle over his first eight holes.
He started on Northview's back nine and tallied birdies on 10, 11 and 12, then holed his approach from the fairway for eagle at the 400-yard, par-4 14th. Tolles added birdies at 15 and 17 to climb to 7-under-par, but he knocked his second shot into the water at the 430-yard, par-4 18th and wound up carding a double-bogey.
Although he managed to make the turn in 5-under 30, Tolles mixed two bogeys with just one birdie on the way in for his 67.
Defending champion Joel Edwards and former Air Canada winners Rory Sabbatini (2000), Mike Weir (1999) and Mark Calcavecchia (1997) were among 27 players knotted at 3-under par with 68s. Also tied there were Scott Hoch, Chris Riley and Fred Funk.
Full-field scores from the Air Canada Championship