O'Hair has enjoyed a solid start to his career on the PGA Tour and has come on in recent weeks with seven straight cuts made. O'Hair is still seeking his first top-10 finish, but a strong third round has left him in position for much more than that.
'I am very excited,' said O'Hair. 'Just going to try to play like I've been playing, and that's been just play for pars and let the birdies come my way. I'm pretty happy with the way I handled myself.'
The 22-year-old parred his first three holes of the day at the TPC at Four Seasons Resort until a birdie at the par-4 fourth lifted him to 10 under par. He gave that shot back with a bogey at the par-5 seventh but maintained his composure and made a move on the inward half.
'I really struggled at the beginning of the day,' he said. 'I was nervous, but I definitely wasn't feeling well.'
O'Hair hit his second shot to the back fringe at the par-4 11th but rolled in a 16-foot putt from off the green for a birdie. O'Hair then played his second shot inside 18 feet at the par-4 12th and drained the birdie try to jump to minus-11.
He hit an errant drive at the 13th that almost found the water but he steadied himself to par the hole. O'Hair followed with pars on each of the next two holes and stayed ahead of his challengers with a birdie at the par-5 16th.
O'Hair hit his tee shot to 15 feet at the par-3 17th but was unable to convert. He added a par at the closing hole to secure a one-stroke lead with one round to play.
'I think eventually I was going to be in this situation, at least that's the goal for everybody who plays out here,' said O'Hair. 'I thought eventually I'd be contending at least for an event. So it's nice to be in this situation, especially this event.'
Hamilton jumped out of the gate with three birdies over his first four holes. He stumbled to a bogey at the par-3 fifth but responded with a birdie at the par-5 seventh.
The 39-year-old hit his second shot to 10 feet for a birdie at the par-4 10th and added a birdie at the par-5 16th to finish alone in second place.
'I haven't played well lately,' said Hamilton. 'I've been doing some things this week that I haven't really been doing this year. I've been making some putts here and there, saving pars when I need to for the most part. Hopefully I can continue one more day.'
Jaxon Brigman fired a 64 to join Shigeki Maruyama and Bob Tway at 8-under-par 202. Nick Price, John Rollins, Jay Williamson and J.J. Henry were one shot further back at 7-under-par 203.
Vijay Singh managed a one-under 69 on Saturday to move to 6-under-par 204 along with Luke Donald, Brett Wetterich, Jesper Parnevik, Stuart Appleby, Bo Van Pelt, Ben Crane, Omar Uresti and Heath Slocum.