The duo was followed closely by Doug Tewell, Tom Jenkins, Allen Doyle and Des Smyth at 8-under-par 132.
Thorpe found trouble early at Green Island Country Club with a bogey at the par-3 second. The dropped shot was the only blemish in Thorpe's round and the five-time Champions Tour winner played solid golf the rest of the way to surge to the top of the leaderboard.
'Every bogey I've made here, I've come back with birdie which made me happy,' said Thorpe.
He birdied the third and hit his second shot to 14 feet for a birdie at the fourth. Thorpe then added a birdie at the sixth and picked up another birdie when his 7-iron landed within seven feet at the par-4 ninth.
Thorpe kept on rolling on the inward half and hit a wedge to six feet for a birdie at the 13th. He then birdied the 16th and capped his round with a birdie at the par-5 18th.
'Solid round,' said Thorpe. 'I played smarter today than I did yesterday. All in all a patient round today.'
Hatalsky, who is seeking his second Champions Tour title, ran home a 25-foot putt at the second and hit a 9-iron to eight feet for a birdie at the fourth. He cooled off from that point until a birdie at the 10th.
Hatalsky kept things going with a birdie at the 15th and birdied the last to close out a bogey-free round.
'The key is keeping it in the fairway because of the wet conditions,' said Hatalsky. 'I've been in the hunt before. I'm familiar with it. You're not going to back into a win here. You're going to have to go for it.'
Tewell, who will play in the final group alongside Thorpe and Hatalsky on Sunday, collected six birdies to go along with no bogeys for a flawless 64.
'I've had some distractions and haven't been focused this year,' said Tewell. 'I just want to have the opportunity to win the tournament with nine holes to play then I know my preparation has been good.'
Jim Ahern and Dana Quigley finished tied for seventh at 7-under-par 133. Tom Kite and Ed Dougherty were one shot further back at 6-under-par 134.
Dave Barr shot a 65 to finish alone in 11th place at 5-under-par 135. He was followed by Wayne Levi, Rik Massengale, Jim Holtgrieve, Larry Ziegler, Bobby Wadkins and Walter Hall at 4-under-par 136.