Long hitting Victor Schwamkrug and David McKenzie share second place at 5-under-par 67. Lee Porter, Sonny Skinner and Knoxville Open winner Hunter Haas are one stroke further back at minus-four.
Stadler, son of Champions Tour player Craig Stadler struggled to a final- round 85 on Sunday to finish next to last at the U.S. Open last weekend. With that behind him, he got off to a hot start with back-to-back birdies from the par-5 second.
After four straight pars, Stadler again converted consecutive birdies from the eighth to make the turn at minus-four. He cruised to four pars in a row, before joining the lead at minus-five with a birdie at the par-5 14th.
Stadler, playing in the final group, gained the overnight lead when he birdied the par-4 closing hole to cap a bogey-free round on the Upper Course at Peek 'n Peak Resort.
'The rain passed through when we were on No. 12 and after that it was great out here,' said Stadler. 'This is a great golf course and you have to golf your way around here. It's a relief to play out here. It's a lot more low key compared to last week and just more my style.'
Schwamkrug began on the back nine and was steady out of the gate with seven straight pars. He then reeled off three consecutive birdies around the turn.
On the front side, Schwamkrug moved to 4-under with a birdie at the par-4 third. The 27-year-old stumbled to a bogey at the seventh, but closed with birdies at the eighth and ninth to share second place.
The Australian McKenzie posted birdies at the third, fifth and seventh, but in between faltered to bogeys at the fourth and sixth. He picked up another birdie at the ninth, to head to back nine at minus-two.
McKenzie moved up the leaderboard with birdies at the 12th, 15th and 17th to tie Schwamkrug in second.
'I had a little wind map with me and I had it all worked out before we went out to play,' McKenzie said. 'I was pretty happy with the map, but it didn't help me once. Still it was nice to get under par and not give them back.'
Anthony Painter, Craig Lile, Ahmad Bateman, Matt Peterson, Brent Schwarzrock, Joe Daley and Jaxon Brigman share seventh place at 3-under-par 69.
Franklin Langham, who won the Rheem Classic earlier this year, is one stroke further back at minus-two. He is joined there by Perry Moss, Brad Ott, Eduardo Herrera, Ben Bates, Rick Price, Byron Schlagenhauf, Dave Stockton, Jr., Jason Buha, Jason Caron and Paul Claxton.