The 52-year-old Goin made six birdies in bogey-free 66. Three-time champion Hale Irwin, the only player to win this tournament more than once, birdied three of his last four holes in a 5-under 67 that left him tied for second with Tom Wargo, Bob Eastwood and Roy Vucinich.
Goin birdied the first two holes on the par-72 Port Course at the Harborside International Golf Center, a public facility built on a former landfill just minutes from downtown Chicago. He added four more birdies the rest of the way, including a pair to cap his round.
'Three 66s would make me very happy,' said Goin, 52, who is in his second season on the Senior Tour and looking for his first victory. 'It's nice to get off to a good start this week.'
All of Goin's birdies came from inside 10 feet. He had a great opportunity to finish with an eagle after reaching the 522-yard, par-5 18th in two, but wound up missing a five-foot putt.
Goin finished in the top-10 three times in 2001, with a tie for fifth at the Enterprise Rent-A-Car Match Play Championship his best result to date. His tie for seventh in his first start of the season, the Royal Caribbean Classic, has been his only top-10 of 2002.
The only other time Goin has held at least a share of a first-round lead as a member of the 50-and-over set was at last month's Senior PGA Championship. He jumped out of the gate with a 68 to tie for the top spot at Firestone but posted 76-79-73 the rest of the way to finish joint 60th, his second-worst showing of the season.
Irwin was the last player to have sole possession of the lead after one round of this event. At Kemper Lakes Golf Club in 1998, Irwin opened with a 10-under 62 -- the lowest round in tournament history -- en route to a three-stroke victory.
He also won at Kemper Lakes in 1999 and at Stonebridge Country Club in 1995.
Irwin, who went back to using an old putter this week, took 26 putts on Friday. His closing stretch featured an eight-foot birdie putt at the 15th, a 15-footer at the 16th and a four-footer at the 18th.
'I'm not one to change equipment very much. I just needed a different look,' Irwin said. 'I'll probably be back to the other putter in time.'
Irwin, who currently leads the Senior Tour money list, was also runner-up in this event in 1997 and a top-five finisher the last two years.
Seven players were two shots back with 68s, including 61-year-old Jim Colbert, Doug Tewell and Jay Sigel, who finished second last year.
Defending champion Dana Quigley added to his Senior Tour record by playing in his 189th consecutive event for which he's been eligible. But it wasn't the start he was looking for in his title defense, as the senior ironman triple bogeyed the first hole on his way to a 6-over 78.
'It knocked my feet out from under me,' said Quigley, who also suffered three bogeys and a double bogey to fall to eight-over after 12 holes. He finished with two straight birdies.
Orville Moodie celebrated playing in his 500th Senior Tour event Friday by carding a 2-under 70, his low round of the year. The 68-year-old Moody, an 11-time winner on the elder circuit, stands third behind Miller Barber (576) and Harold Henning (520) in career starts.
Full field scores from the SBC Senior Open