Gavin Coles, Brett Wetterich, Euan Walters and Jason Caron finished one shot off the lead at 6-under-par 66. Scott Gutschewski was tied with Stiles atop the leaderboard, but a double bogey at the closing hole left him in a tie for sixth at 5-under-par 67 alongside Doug Barron, Jeff Klauk, Ben Bates, Franklin Langham and Justin Bolli.
'I'm not worried about the top-20 this week,' said Stiles. 'My whole mindset this week is that I want to win the event, that would make it a complete year for me.'
Stiles was on fire early and jumped out of the gate with a birdie at the opening hole. He added a birdie at the par-4 third and another at the par-4 sixth. Stiles then birdied two in a row starting at the par-5 eighth to go out in 31.
The 31-year-old, who is currently ranked 16th on the Nationwide Tour money list and in position to earn his PGA Tour card for next year, dropped his tee shot inside 20 feet at the par-3 13th and drained the putt to move into the lead at 6 under.
Stiles then hit his approach to 8 feet for a birdie at the par-4 15th and landed his tee shot within 3 feet of the hole for a kick-in birdie at the par-3 16th to keep ahead of his challengers at minus-8.
Stiles parred the 17th, but struggled coming home with a bogey at the par-4 18th. Despite the late mistake, Stiles managed to stay on top the leaderboard after the opening round.
'I know I've got to play well just to stay where I'm at on the money list,' said Stiles. 'I'm more focused on one thing, winning, over another. The idea is to play to win versus playing to hold my spot.'
Coles birdied each of his first two holes and reached 3 under with a birdie at the par-4 ninth. He kept plugging along with a birdie at the 11th and converted a 9-foot putt for a birdie at the par-3 13th to keep pace with Stiles.
The Australian then birdied the 15th and sank a long birdie putt at the 16th to move to 7 under. Coles was scrambling at the last, however, and ultimately missed a 15-foot putt for a closing bogey.
Wetterich managed a trio of birdies over his first nine holes and continued his fine play with a birdie at the 10th. He stumbled to a bogey at the 12th, but recovered well with back-to-back birdies from the 14th. Wetterich then ran home a 16-foot putt for a birdie at the par-5 17th for his share of second.
Caron birdied each of his last three holes to move within one of the lead, while Walters managed seven birdies and a bogey.
'I know this is a big week and I need to finish first or second,' said Caron, who is currently 36th on the money list. 'I'm trying to get things going like they were for me earlier in the year.'
Kevin Stadler, Chris Tidland, Jon Mills, Scott Petersen, Nathan Green and Jason Schultz finished three shots back at 4-under-par 68.