Jim Ahern, the tournament winner in 1999, was part of a large group four shots off the lead. He was joined by Stewart Ginn, Morris Hatalsky, Bobby Wadkins, Allen Doyle, Tom Wargo and Mark Pfeil at 4-under-par 67.
Jenkins earned his second career victory on the Senior Tour at this tournament two years ago when it was played at St. Charles Country Club. This year at Essex Golf & Country Club in Ontario, the change of scenery proved to be of little adversity.
At the opening par-4, Jenkins hit his second shot four feet from the cup for a quick birdie. Two holes later at the par-5 third, Jenkins reached the green in two and rolled home a 15-foot putt for eagle to move to minus 3.
Jenkins then ran into a tough couple of holes starting at the fourth after a bad iron resulted in a bogey. Jenkins added another bogey two holes later, but soon enough the spark returned to his round.
Jenkins knocked an 8-iron inside 12 feet for a birdie at the seventh, then made it two in a row with a birdie at the very next hole. At the ninth, Jenkins was on the green in two but had a very long try for birdie. The 54-year-old calmly drained the 40-footer for his third consecutive birdie to make the turn at 4-under.
The native of Texas two-putted for birdie at the par-5 10th and picked up two straight birdies from the 12th to move to minus 7.
At the 15th, Jenkins ran home a 25-foot putt for birdie to reach 8-under and match his lowest career round on the Senior Tour.
'I had zero expectations this week,' said Jenkins, whose 63 also tied the Essex course record established by Jerry Pate at the 1976 Canadian Open. 'I've been a little under the weather. I've just been trying to get more rest.'
Jenkins was also playing through illness when he won the tournament in 2000.
'When I won in 2000, I came within 10 minutes of withdrawing,' said Jenkins. 'This could be a sign. When you're sick, you're not thinking so much about golf. You've got to let your troops inside play golf. They know how to do it. They will surprise you sometimes.'
Hamilton, the head professional at Mississaugua Golf & Country Club, which played host to the tournament in 2001, had eight birdies and two bogeys for a round of 65. The round was the best ever by a Canadian at this event.
'The key to this course is hitting it in the fairway,' said Hamilton. 'I feel I have a chance to compete. I'm thrilled to be here and represent Mississaugua.'
Defending champion Walter Hall finished five shots off the pace after a round of 3-under-par 68. Hall was joined by Butch Sheehan, Jack Spradlin, Bruce Summerhays, John Schroeder, Isao Aoki, Ed Dougherty, Bob Eastwood, Hale Irwin and Bill Kratzert, a four-time winner on the PGA Tour who is making his debut this week on the senior circuit.
Full-field scores from the AT&T Canada Senior Open