Brian Davis lies in a tie for third at the halfway stage of the Crowne Plaza Invitational in Fort Worth, Texas.
Bryce Molder leads by one stroke at 13 under after an eight under 62, while Englishman Davis sits in a two-way tie for third on 11 under.
Davis' five under 65 came despite having overnight hospital treatment to remove a mouth abscess.
"It's just one of those things, I went last night and had it taken care of," said Davis.
"Obviously I've got a lots of swelling still so it will take a few days to go down, but I'll be fine."
Leader Molder said after his round: "It's a good position, one of the last groups on Saturday, and I can have some fun.
"It's been a strange two days with no breeze, really warm, but really good scoring conditions and fortunately I was just able to capitalise."
Jason Bohn remains well in contention in second, a shot off Molder, having recorded a 65 after Thursday's 63.
Sweden's Carl Pettersson is nine under, while his compatriot Henrik Stenson, Argentine Angel Cabrera, England's Paul Casey and Scot Martin Laird are all four under, in a tie for 36th, nine shots off the lead.