Sheehan got off to a flying start with birdies at one and two. After a par on the third, he moved to minus-3 with a chip-in birdie on the par-3 fourth. The 35-year-old came right back with a birdie on the fifth.
'Well, I got off to a great start,' Sheehan said. 'I hit the fairway on the first hole, which is no easy thing to do. I hit a poor bunker shot with my third, but made a nice 15-footer from there. And then it got crazy from there.'
The Rhode Island native kept rolling with another chip-in birdie on the sixth. Sheehan made it four straight birdies at the seventh. He climbed to 7 under with a birdie on the eighth at Colonial Country Club.
Sheehan, however, stumbled to a double bogey at the ninth after a bad tee shot to make the turn at 5 under. The University of Hartford alum caught fire again on the back nine.
He drained a 40-foot birdie try on No. 10 and got up and down for birdie from a bunker on the 11th. Sheehan sank a birdie putt from just inside 12 feet out at the par-3 13th to get to minus-8.
Sheehan converted a stellar up-and-down par on 15 and came back with a birdie on 16 from 13 feet out to get to minus-9.
With the magical 59 and the course record of 61 in his sights, Sheehan could only par the 17th. He then stumbled to a bogey at the last after his tee shot found the trees left of the fairway to end at minus-8.
'On 17, my caddie and I were thinking about 59 if we birdied the last two holes,' said Sheehan. 'It didn't happen, but that's alright. It was a great round.'
Trahan started on the 10th tee and jumped out with birdies on 10 and 11. He slipped to a bogey on the 12th, but rebounded with a birdie on the 14th. The Clemson University alum moved to 3 under with a birdie on the 17th.
Around the turn, Trahan picked up another birdie on the first to get to 4 under. The 24-year-old carded his sixth birdie on the third, but faltered to a bogey at the next to drop back to 4 under. Trahan collected two more birdies on his way in to share second place.
Bateman also got off to a good start as he eagled the par-5 first. He ran off back-to-back birdies from the fifth to move to 4 under. However, the 32-year-old stumbled to a bogey on the seventh.
He came right back with a birdie on the eight to make the turn at minus-4. Bateman then birdied the par-5 11th. He moved into a tie for second with a birdie at the par-4 17th.
Ted Purdy, who won the EDS Byron Nelson Championship last week, opened with a 4-under-par 66. He shares seventh place with Stephen Leaney, Harrison Frazar, Rod Pampling and Kirk Triplett. Billy Mayfair and Justin Leonard lead a group of six players one stroke further back at minus-3.
Steve Flesch, the defending champion, had his streak of eight straight rounds under par snapped as he opened with a 8-over 79. He is in next-to-last place.