Thomas, who fired a 63 Thursday for a three-shot lead but slipped to 74 on Friday, made five birdies to offset a double bogey and a bogey to finish at 9-under 207 heading into Sunday's final round with more windy conditions in the forecast.
"Some positive vibes there", List said.
India's Anirban Lahiri shares third place with Leishman and will play in the final group with Brown and Thomas as he takes aim at a maiden PGA Tour victory.
Brown had back-to-back bogeys on Nos. 15 and 18 for a 71 and a share of the two-shot lead.
Rod Pampling and Ryan Ruffels both battled in the third round, Pampling signing for a 79 while Ruffels limped to an 81 that included three double bogeys in his first nine holes.
The second-round 74 is Thomas' worst score since an 80 in the second round of the British Open.More news: Liam Payne's New Song Is Full Of Breakup (And Makeup) Sex
More news: Trump to allow release of thousands of JFK files by National Archives
More news: Resident Evil Revelations For Nintendo Switch Adds Exclusive Minigames
Jason Day is next best of the Australians at T16 after a 1-under 71 to be six off the pace while Adam Scott produced his best round of the week, a 2-under 70 that outs him at 1-over and T28.
Perez signed for a bogey-free card after a round-of-the-day 68, with Brown, Luke List, Brian Harman and Jamie Lovemark also ending the week on five under.
TAIPEI, Taiwan - Jenny Shin shot a 5-under-par 67 for a share of the lead with Eun-Hee Ji after the second round of the Taiwan Championship on Friday.
Leishman birdied his opening two holes but carded three bogeys in a four-hole stretch from the fifth, before picking up a shot at the ninth and adding further gains at the 12th and 14th. The leaders are at 7-under 137, one ahead of Brittany Altomare, who carded a 68.
RICHMOND, Va. - Bernhard Langer birdied the par-5 18th for a 5-under 67 and a share of the first-round lead Friday in the Dominion Energy Charity Classic, the first event in the PGA Tour Champions' Charles Schwab Cup Playoffs. Rocco Mediate, David Toms and Joe Durant matched Langer atop the leaderboard at The Country Club of Virginia's James River Course.