Roberts made four birdies for a 7-under 133 after 36 holes. Hoch shot a 68 and was alone in second place in the Champion Tour's final major tournament of the year.
David Eger shot a 67 for a 136, tied with Des Smyth, who completed his 66 with a bogey on 18.
Roberts began the day in a five-way tie atop the leaderboard. He saved par on the 427-yard first hole, blasting out of the left bunker to within 10 feet of the hole before sinking the putt.
'I think that settled me down or spurred me on or something, because I really played solid the rest of the day,' he said.
Roberts made birdie putts ranging from 4 to 12 feet on Nos. 5, 6 and 15. His best shot of the day came on the 496-yard par-4 18th, when he hit a 3-iron from 208 yards to within 2 feet of the pin before tapping in.
Only one player birdied the 18th hole during the first round; Roberts and Hoch were among five who did it Friday.
'It's a tough hole. It's surprising, and it feels good to do it,' Hoch said.
Roberts' final birdie provided him with a bit of separation from the rest of the field, although he wasn't ready to begin celebrating.
'Halfway through it doesn't matter. I think the only time it matters is when you make that turn on Sunday and you're on the 10th hole,' he said.
Roberts' birdie on 18 was a product of his approach; Hoch made his by sinking a twisting putt of 26 feet, 7 inches.
'When it got about two feet from the hole I thought, man, here's another one I'm going to leave just short,' Hoch said.
Playing under cloudy skies, Hoch repeatedly left his putts short of the hole. He blamed the shortcoming on the heavy greens.
'I guess it's because there's a little moisture in the air and the sun has not come out to dry them out like yesterday afternoon,' he said. 'Today I just couldn't quite get it to the hole, but I hit enough good shots and recovered from the not-so-good shots to still have a good round.'
Hoch's only bogey was on No. 3, when his drive hit the top of the bunker and rolled down. He rebounded with a birdie on No. 4, sank a 15-foot birdie putt on No. 7 and parred the next 10 holes before going out with a flourish with a wicked putt on the 18th.
'On the hole before I had about the same putt, maybe 5 feet farther,' Hoch said. 'It just died short of the hole dead in the middle.'
Seven golfers were at 137, including first-round co-leader Mark Wiebe, Fred Funk and Tom Watson, who stumbled with a double-bogey on the par-4 16th hole.
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