Robert Karlsson retained the lead at the FedEx St Jude Classic but came under pressure as Harrison Frazar put a big run together in Memphis.
Frazar shook off an early bogey to sign for a six under par 64, with birdies on three of the last four holes.
The round, joint-best of the day alongside Retief Goosen, propelled him to ten under for the tournament, one shot behind Karlsson and two ahead of third-placed John Merrick.
Karlsson finished two under par on the day after a pair of bogeys on the final two holes cost him vital ground going into the final day's play.
"I hit a poor shot on 17 and on 18 pushed my driver," Karlsson said. "I'm still very happy. I played well here last year so I'm looking forward to [Sunday]."
Merrick went round in 67, having got off to a blistering start with three straight birdies before cancelling out a bogey on the fifth with a birdie on the 18th.
Goosen's 64 saw him move from a share of 19th to fourth place outright, ahead of Fredrik Jacobson and Keegan Bradley, as he made four birdies over the last five holes.
"You have to grind it out there," Goosen said. "It's not one of the longest courses we play on tour, but it's very tricky and especially these breezy conditions and the heat. The greens are getting crusty out there, too."
