Iain Steel, Ryuji Imada, Sonny Skinner and Zoran Zorkic share second place after opening rounds of 7-under-par 65.
Boros, who won the Lake Erie Charity Classic at Peek 'n Peak Resort this season, chipped in for birdie at the 10th and it would not be the last time the 38-year-old's short game helped him.
He went on to add birdies at 12 and 17 and collected a birdie at his 10th, the first at Yankee Trace. Boros then chipped in twice in his last four holes to take sole possession of first place.
'Coming in here you have to have the mindset to make a lot of birdies,' said Boros. 'If you miss an eight- or 10-footer you feel bad because you've let one slip away. Usually 20- or 22-under is not my kind of golf course. Eight to 10-under is more my style.
'My game just keeps getting better. My confidence is so much better, especially after winning at Erie.'
Yankee Trace took in a lot of rain over the week and that led to Boros' best score on the Nationwide Tour since a second-round 63 at last fall's Gila River Golf Classic in Arizona.
'This golf course is one of the best we play all year,' said Boros. 'It's in great shape and nice and soft after the rains here the past two nights. With no wind, there will be some low ones today.'
Skinner, who shared the 54-hole lead last week at the Henrico County Open, continued his hot play with seven birdies and 23 putts on Thursday.
'I just pretended I was back in Sylvester, Georgia and was making birdies at Pineknoll Country Club,' said Skinner. 'You have to set a new par value when you play here. That's how you have to look at it. Everyone is making birdies so you just set the bar at 68 and try to shoot under par.'
Steel tallied five birdies and an eagle for his round of 65, while Imada and Zorkic recorded their bogey-free rounds with seven birdies.
Ryan Palmer, Rick Price, Han Lee, Bubba Dickerson, Chris Couch, Zach Johnson and Jason Hill share sixth place at 6-under-par 66.