The trio matched the course record at Hualalai Golf Club on Friday. Tom Kite established the mark in 2002, then Fuzzy Zoeller tied it one year later and Craig Stadler posted the score in 2004.
Curtis Strange, the two-time U.S. Open winner, who only got into the field when Lee Trevino withdrew, took advantage of his opportunity. He shot an 8-under-par 64, his lowest on the elder circuit, and is alone in fourth place.
Zoeller, Ben Crenshaw and Jim Thorpe are tied for fifth place at 7-under-par 65.
Scoring conditions were optimum on Friday with no wind and a relatively defenseless golf course. Only two of the 35 players in the field failed to break par and the scoring average was an eye-opening 67.5.
Watson was 3 under through his first five holes, but got the round going with a 45-foot eagle putt at the par-5 seventh. He closed his front-nine 30 with a 4-footer for birdie at the ninth.
The reigning Charles Schwab Cup champion collected back-to-back birdies when he rolled in another 4-footer at No. 10. He parred his next two, but quickly returned to his birdie ways.
At the 13th, Watson played his approach inside 3 feet and tapped in for birdie. He made it two in a row at 14 as he had only 25 feet for eagle. Watson missed that putt, but kicked in the short birdie try to reach 9 under par.
Watson did not give himself many good looks on his way into the clubhouse. He made routine, two-putt pars at 15, 16 and 17, but had 16 feet for birdie at the last. Watson's putt died left, but he made the par attempt to finish in great position.
'You never know with the first round of the year,' said Watson, who lost to Dana Quigley in a playoff last year at this tournament. 'I was thinking real low after the 14th hole, but it wasn't meant to be.'
Roberts, who won the Tradition last season, flew out of the gate on Friday with five birdies in his first seven holes. Roberts' biggest shot of the round did not yield a birdie, but saved a par. At the ninth, he found a fairway bunker and played his second to the left intermediate cut. Roberts stuck his third inside a foot to save par.
'This saved the round,' admitted Roberts.
Roberts parred his next three after the great save at nine. At 13, he hit a 7-iron 6 feet below the hole and converted the birdie putt. His second at the par-5 14th ran through the green, and he nearly holed the eagle chip, but settled for a birdie. Roberts made it three in a row when his 6-iron approach at 15 stopped 5 feet from the hole.
At the par-3 17th, Roberts hit a full 9-iron to 7 feet. 'The Boss of the Moss' stroked home the birdie putt, then narrowly missed a 13-foot birdie putt at the last.
It hardly mattered as Roberts established his new best score on the Champions Tour.
'It is a great start,' said Roberts, who stated he will play close to six events on the PGA Tour this season because he is Tom Lehman's assistant captain at the Ryder Cup. 'I'm thrilled to death to be here. I hit the ball really well.'
Pooley, the 2002 U.S. Senior Open champion, missed a short birdie putt at the second hole, but that would be his last miscue. He tallied three birdies in a four-hole span on the front nine, but it was his play at the start of his second nine that earned him his piece of the lead.
Pooley birdied his first five holes on the back nine to get to 8 under par for the championship. He barely missed birdie putts at 16 and 17, but cashed in from 16 feet at No. 18 to join Watson and Roberts in first.
'I'm looking forward to this year,' said Pooley, who recently completed swing changes. 'I still have a ways to go, but I like where it's going right now. You never know what you're going to shoot in the first round of the year. All of a sudden, things started working just fine.'
Mark Johnson, D.A. Weibring, Bob Gilder, Allen Doyle, Tom Jenkins, David Eger and Peter Jacobsen are tied for eighth place at 6-under-par 66.
Quigley carded a 5-under-par 67 and is part of a group tied for 15th place.