Mark Wilson was in the lead at minus-14, but bogeyed his last two holes to card an even-par 70. He stands at 12-under-par 198 and was joined there by Robert Gamez (68) and second-round leader Dean Wilson (70).
J.J. Henry fired a 4-under 66 Saturday to move into a share of fifth place at minus-11. He was tied there by John Senden, Bob Heintz and Jeff Maggert.
Austin started the day two strokes behind Dean Wilson. Austin fell further back with a bogey on the first. He battled back with a birdie on the second.
The 41-year-old parred his next four holes. Austin dropped another stroke at the par-4 seventh. He atoned for that error with a birdie on the eighth.
Austin tripped to his third bogey at the ninth to make the turn at minus-9. He settled in with four consecutive pars on the Resort Course at LaCantera Golf Club.
The two-time winner on the PGA Tour then eagled the par-5 14th to move to minus-11 after hitting his approach from 202 yards out to 2 feet.
Austin rolled in a birdie on the 16th to get within one of Mark Wilson's lead. After Wilson bogeyed the last, Austin birdied the same hole to take the out-right lead after three rounds.
'It's all new, but it's all new in a good way, so there's nothing wrong with that,' said Austin, who leads entering the final round for the first time in his tour career. 'I've played in one final group, and that was just this year at Hartford. I was trying to defend. I haven't had too many of these.'
Mark Wilson got off to a good start with a birdie on the first. He ran off three straight birdies from the sixth to jump into a tie for the lead at minus-12.
The 30-year-old climbed into the lead by himself with a birdie on the par-4 11th. Wilson moved two clear of the field with a birdie on the par-5 14th. However, he tripped to back-to-back bogeys from the 17th to fall one behind Austin.
'I wasn't focusing on my target anymore, I was just kind of hoping it on the green,' said Wilson of his approach on 18. 'I had a great look at the hole and I didn't trust that the wind was going to push it, and I was aiming left center of the green and I didn't trust it. So I hit it at the flag and hit it in the bunker.
'So the finish was a bummer, but I really putted well early, so I'll try to recreate that tomorrow.'
Dean Wilson, no relation to Mark, birdied the first. He faltered to a bogey on the next though. He parred his next seven holes, but stumbled to another bogey on the 10th.
The 35-year-old got one stroke back with a birdie on the 12th. After a bogey on No. 13, Dean Wilson birdied the 14th to get back to minus-12. He parred his next four holes to share second place.
Gamez, who led after the first round, birdied the first, but bogeyed the second. After a pair of pars, he rolled in a birdie putt on the par-4 fifth.
The 37-year-old parred eight consecutive holes around the turn. Gamez birdied the par-5 14th to get to minus-12. He got within one of Mark Wilson's lead with a birdie at the 16th. However, Gamez bogeyed the next to drop back to 12 under and a tie for second.
Steve Lowery posted his second straight round of 4-under 66 on Saturday. He stands at 9-under-par 201 and was joined in a tie for ninth place by Olin Browne (71) and Alex Cejka (68). Paul Claxton is one stroke further back at minus-8. Bart Bryant, the defending champion, is tied for 15th at 6-under-par 204.