Uresti, a 10-year PGA TOUR veteran, stands at 6-under 138 for a three-shot lead over Ben Bates.
'I'm happy with how I've played,' he said. 'Three days ago I would have never guessed I would be this position. I was really struggling with my game.'
Bates had a 2-under 70 to stand alone in second place at 141 overall. Aaron Watkins (72) and Jon Mills (73) are a shot further back at 142.
Uresti posted five birdies Friday and was as low as 8 under before a double-bogey at the par-4 17th ended his string of 34 straight bogey-free holes.
He made three birdie putts longer than 15 feet, including a 45-footer at the par-5 eighth.
'I made a little adjustment to my grip and now I'm rolling them in,' said Uresti, who won his only PGA TOUR-sanctioned title at the Nationwide Tour's 1994 Shreveport Open.
While Uresti has spent most of his professional career on the PGA TOUR, Bates has spent the lion's share of his on the Nationwide Tour.
Playing in his 332nd Nationwide Tour event, Bates hit 13 fairways and 15 greens in regulation Friday and made five birdies with three bogeys.
'I've played two solid rounds of golf,' said Bates, who owns the Nationwide Tour record with 194 career cuts made. 'This is one of the most demanding golf courses you'll ever play. Steady is the way to go this week. If you're steady every day you're going to be close on Sunday.'
On Thursday, the Course at Wente Vineyards yielded the highest scoring average in nine months.
Friday, the track's level of difficulty was highlighted by Greg Chalmers' 13 at the par-3 14th hole, which dropped him 100 places at the time from a tie for ninth at 1 under par into a tie for 109th at 9 over.
Chalmers rebounded with birdies on the next two holes, but missed the 4-over cut line by three strokes.