"Believe it or not, I was thinking about it going down 16, 17, 18," he said. "If I could have just gotten those balls in play, I would have been defending champion here. But this year, I got off to a good start and obviously a little more focused on those last two holes. Hopefully I'm there again this year."
His 28 on the back nine was the lowest nine holes on the PGA Tour this year, and puts him one shot up on Hunter Mahan, who posted an early 62. Bubba Watson was two strokes back.
Hoffman said he thought he might have a chance to go even lower, and was flirting with 59 after making eagle on 10 and 12, and going to 8-under par with a birdie on the 16th hole.
"I knew I had some chances coming in," he said. "But when it's said and done, as I displayed last year, 16, 17 and 18 aren't an easy test. So I was just trying to make some pars coming in."
Hoffman, Mahan and Watson all have interesting histories in Connecticut.
Mahan is the 2007 champion and has two second-place finishes in his 11 previous starts at the TPC River Highlands.
"I think this is the most comfortable course on Tour for me," he said.
Charley Hoffman -9
Hunter Mahan -8
Bubba Watson -7
Six tied at -5
Daniel Summerhays +1