Michael Muehr, Jerry Kelly and Bob Heintz are alone in second place at 6-under par, followed by Chris Smith and David Gossett, who share fifth at minus 5.
Roberts, known as the 'Boss of the Moss,' lived up to his nickname Thursday. He needed only 24 putts to make his way around the West Course at Westchester and also brought a short game that kept him near the top of the leaderboard.
'I just happened to have a great day with the putter,' said Roberts. 'I had an impossible chip-in and made a couple of long putts. I hit a couple of really good iron shots at the right time from tough pins, and I just kind of got on a roll today and hit it on the right spots.'
Roberts opened on the second nine and was even through seven holes and seemed to be in trouble at the par-4 17th. He drove into the right rough and blew his second shot over the green, leaving him with a difficult chip to even get close to the pin. Roberts holed the chip for a birdie when a bogey-5 looked like a certainty.
The 46-year-old gained momentum after the chip-in at 17. He drained a four-foot birdie at 18 and made it three in a row when he nearly holed a 4-iron at one but settled for the eight-foot birdie instead.
Roberts birdied three more in a row starting at three and closed his round with 20-foot birdie from the fringe at No. 7.
'I love this golf course,' said Roberts. 'Especially since they have come in and redone the bunkers and made this golf course a lot tougher. A couple of shots are tougher, just because it's really tough to get the ball up-and-down from the short-side now.'
Roberts may not have looked like a strong candidate to be the first-round leader after enduring some disappointment earlier in the week. He shot a 2-under-par 141 at the U.S. Open sectional qualifying in Maryland and missed an entry at Bethpage Black by two shots.
'There's been two Opens in the last ten years that I really wanted to play in, and that was Pebble Beach and this one,' said Roberts, who lost to Ernie Els in a playoff at the 1994 U.S. Open. 'I'm sorry I'm not going to be in. But I've just got to redefine my schedule for the year. I'm here, so I'm going to try to win the golf tournament here.'
Muehr had a different story to tell about sectional qualifying at Woodmont Country Club in Rockville, Md. He closed bogey-double bogey to narrowly make it into a playoff for the final spot. On Tuesday, he won the third playoff hole to outlast 11 other men for the last berth.
'I finished bogey-double bogey to get in that playoff,' Muehr said. 'I almost didn't show up Tuesday. I just kind of went out with nothing to lose and stole that spot. That's the kind of thing that can turn your year around.'
Retief Goosen, preparing for his U.S. Open title defense next week, shot a 4-under-par 67 in the first round. He shares seventh place with Jim Carter, Stewart Cink, Steve Elkington, Pat Perez, John Rollins, Craig Parry and Robert Allenby.
Sergio Garcia, the 2001 Buick Classic champion, headlines a group at 3-under par. Memorial winner Jim Furyk, Fred Couples, Tom Lehman and Els are also part of the logjam tied for 15th.
Full-field scores from the Buick Classic