Wagner entered the third round with a three-stroke lead but started slowly, making three pars before a birdie on the fourth. He then shot a bogey five on the fifth when he missed a six-foot par putt.

“I was definitely nervous starting the day,” he said.

“I had some good chances early. But putts weren’t really falling, and I made a bad bogey on five.”

Wagner responded with three birdies in four holes from the ninth through to the 12th.

“I really held it together, hit a bunch of greens – and didn’t really have to work too hard,” he added.

Estes, who began the round eight strokes behind, erased five of them with a front-nine 31. Three straight birdies then followed from the 11th to the 13th.

Campbell caught Wagner at 12 under when he holed out with a wedge from 88 yards - and then again at 13, 14 and 15 under – until he made a bogey on the 17th, failing to get up and down from a greenside bunker.

Fred Couples, who was in a tie for 36th, pulled even with six others for 10th by signing for a 67.

Phil Mickelson, the highest-ranked player in the field, carded a one under 71 to be 22nd.

With no realistic chance to win, Mickelson is already looking to next week and The Masters at Augusta.

“I’m going to try to get a good solid round and see if I can make some birdies and get momentum for next week’s Masters,” he said.