A pair of two-time Long Island winners in Bruce Fleisher and Lee Trevino were part of a group at 5-under 66. They were joined by Howard Twitty, Walter Hall and 2002 U.S. Senior Open champion Don Pooley.
Irwin coasted at even-par until his first birdie of the day at the par-3 seventh. Irwin knocked his tee shot inside 12 feet and drained the putt before picking up another birdie at the following hole to make the turn at minus two.
The 57-year-old caught fire on the inward nine at Meadow Brook Club. He two-putted for birdie at the 10th and hit a two-iron to six feet for birdie at the 12th.
Irwin converted from 10 feet for birdie at the par-4 14th and hit his second shot within four feet for birdie at the 16th to climb to 6-under.
At the par-3 18th, Irwin hit a six-iron inside eight feet of the cup for his seventh birdie of the day.
'A very good start,' said Irwin who has won twice this year as well as a victory at the Senior Skins Game in January. 'I played nicely from tee to green. I had one of my better ball-striking days in a while. I made a slight change in my stance last week while I was in St. Louis. Now I've got a stiff back but thank God for the warm weather. The conditions were good for scoring.'
Morgan also put together a bogey-free round to finish alone in second. He picked up back-to-back birdies from the first and added another pair at seven and eight to make the turn at 4-under. He added a birdie at the 10th and ran home a 12-footer for birdie at the 13th and a round of 65.
'I had a pretty fast start with birdies on the first two holes,' said Morgan. 'The course was pretty receptive.'
Fleisher, who won three times in 2001, has yet to grace the winner's circle this year. The 53-year-old collected six birdies and one bogey to finish two shots off the pace.
'I've been struggling on Friday's,' said Fleisher. 'I think certain golf courses look good to certain players. I like this course. I've had three wonderful years out here.'
Trevino, fresh off an appearance at the Battle at Bighorn this past Monday, played a flawless round with five birdies and no bogeys.
'I wasn't in anything that was close to trouble all day and I putted real well,' said Trevino. 'I would love to play the next two days the same way.'
Dick Mast, Jay Overton, Morris Hatalsky, Hubert Green, John Schroeder, Stewart Ginn and Tom Kite finished three shots off the pace at 4-under-par 67.
Defending champion Bobby Wadkins, who became the youngest player to win a Senior Tour event in last year's tournament, had three birdies and three bogeys for a round of even-par 71 alongside Bob Gilder, who is seeking his third straight win.