Steve Pate, who shared the lead entering round three with Harrison Frazar, posted a 3-under 69 to share second place with Chris Couch. Couch shot a 68 and stands alongside Pate at 15-under-par 201.
Greg Chalmers (67), Kevin Na (66) and John Senden (69) are one stroke further back at minus-14.
Funk, who was a member of the U.S. Ryder Cup squad, opened with a birdie at the first, but tripped to a bogey at the very next hole. He eagled the par-5 fifth to get to 10 under and start a solid stretch of golf.
The 48-year-old came right back with a birdie at the sixth and made it two straight when he found the cup for birdie at No. 7. The five-time winner on the PGA Tour made it three in a row when he birdied the eighth.
Funk picked up his fifth birdie of the day at the par-4 10th. He settled in with six consecutive pars starting at the 11th at Annandale Golf Club.
The University of Maryland alum closed in fine fashion. Funk converted a birdie at the 17th and made it two straight to close his round as he drained a birdie on the 18th.
'I made a lot of birdies today and one eagle,' Funk said. 'I finally hit the fairway on five and I got rewarded today as I made eagle. Obviously everyone is making lots of birdies so you have to get as many as you can. I still have to go low on Sunday to have a chance at winning this.'
Pate cruised through the opening nine at minus-1 as he carded a lone birdie at the par-5 fifth. Around the turn, the 43-year-old moved to minus-14 with a birdie at the par-4 10th.
Pate, a six-time winner on the PGA Tour, stumbled to his first bogey in 37 holes at the 14th. However, he responded with back-to-back birdies from the 15th to post a 69 and grab a share of second place.
'Everybody on that leaderboard can play obviously. Whoever plays better on Sunday has the edge,' said Pate. 'If it comes down to somebody who's been there and somebody who hasn't, it helps to have gone through the situation before.'
Couch, a three-time winner on the Nationwide Tour, birdied the fifth for the second straight round to move into red figures. He then eagled the par-5 seventh to jump to 14 under. Couch collected his final birdie at the 11th before parring his final seven holes.
Couch is still playing thanks to Brendan Pappas. Last year, Pappas loaned Couch $3,000 so he could keep playing on the Nationwide Tour. The confidence Pappas showed in him helped Couch turn his season around and earn his PGA Tour card for this season as he finished fourth on the Nationwide Tour's money list.
'If Brendan hadn't been there, who knows what would have happened,' Couch said. 'I wouldn't be on the PGA Tour this year. I feel very fortunate that Brendan helped me out.'
Kirk Triplett fired a 7-under 65 to jump to 13-under-par 203. He shares seventh place with Pat Bates, J.J. Henry, Ryan Palmer, Carl Pettersson and Loren Roberts.
Tim Clark, Bill Glasson, Lucas Glover, Ted Purdy and Camilo Villegas are one stroke further back at minus-12.