An outward nine of one-under 34 earned him a share of the lead with Cox and he was the only title contender to negotiate the treacherous closing stretch without a bogey.

Although six players had been within a stroke of the lead before Maggert reached the turn, he tightened his grip on the tournament with a birdie-two at the 11th followed by a run of four consecutive pars.

He reached the green in two with a superb two-iron from 260 yards at the par-five 16th and stretched his cushion to three by holing the monster putt.

Maggert's fourth birdie of the day at the difficult 17th allowed him a stress-free walk down the last.

Pernice had to settle for his best finish and third top-10 of the season, having narrowly escaped a penalty after unintentionally touching his ball with his putter on the 14th green.

After looking at television replays, rules officials decided his ball had not been advanced and his two-putt for a bogey-four would stand.

"I wasn't aware that I nudged the ball," said Pernice, whose last PGA Tour victory came at the 2001 International.

"The official looked at it a bunch of times and said that it looked like, when I set my putter down, the ball oscillated and moved back.

"I played nice today but obviously Jeff had a great round."

Twice winner David Toms carded a 71 to finish in a tie for 10th at one under, two ahead of defending champion Justin Leonard, after a 73.