Scott and Johnson Wagner both shot a 9-under 63, breaking the Redstone Golf Club's Tournament Course single-round record. Wagner and Bubba Watson set the mark last year with 64.
Scott said he came close to withdrawing.
"But I just don't like withdrawing from tournaments," he said. "I've only done it once, I believe, in my career, and I was pretty bad that day. I wanted to at least get out there and see how I was going. It's a good way to start."
Wagner played the last five holes in 5-under to grab a share of the lead.
"It was more than I expected," Wagner said. "You can never wake up and say I'm going to shoot 9-under."
Newt Gingrich fires back at Mandela backlash
Campus cop fatally shoots Texas student during traffic stop