Duval, the joint leader after Thursday's first round, shot a 69 on Friday, after starting with two bogeys.

His first-round co-leader Hidemichi Tanaka also struggled and was one shot back after capping his 70 with a birdie.

Loren Roberts, Corey Pavin and Charles Howell III were among a group of six on 135.

Duval's errant driving often left him in the heavy rough but Mayfair had no such trouble.

He birdied all four par threes, and all three par-fives in his second trip over the 6,853-yard River Course at Kingsmill Golf Club.

"It's been a tough year. Besides finishing fifth in the US Open, it's been a hard year," he said.

Mayfair's good fortune culminated at the par three 17th when, as the breeze picked up, he hit it straight on the green.

Duval was less chipper after hitting just six fairways and needing a good up and down from the rough to finish with a par.

"I'm just happy to be done," Duval, twice a previous winner, said after the round.

"I'm just not quite as sharp as yesterday but I went off pretty good and managed to play a few shots out of the rough that kind of saved my round."

After starting the day six shots behind Duval and Tanaka, Mayfair said his iron play was his best of the year, and that made his putting better.

"It doesn't matter how good or bad you're putting - if you're putting 35 or 40 feet from the hole, you're not going to make a lot," he said.

US Ryder Cup captain Curtis Strange, playing as a tournament host for the last time, shot a 78 and missed the cut by 11 strokes.