Wolff, who shot the joint-lowest round of the tournament, now leads the second men's major of the golfing year at Mamaroneck, having started the day in a five-way tie for seventh place.

Birdies at the first, fourth, sixth, seventh and ninth holes helped Wolff go out in 30.

He dropped his first shot of the day at the 16th but finished with a birdie at the last to return in 35 and seal a round of 65, taking him to the top of the leaderboard and a score of five under.

He leads by two from compatriot Bryson DeChambeau who shot a level-par 70 to finish at three under.

DeChambeau's day got off to a bad start as he bogeyed the first two holes, before getting one back with a birdie at seven.

He then birdied the 16th and 17th but dropped a shot at the last to finish two behind Wolff.

Two shots further back in third place is South Africa's Louis Oosthuizen, who sits at one under after shooting a two-under-par round of 68.

One shot further back in a tie for fourth place are Japan's Hideki Matsuyama and two Americans - Xander Schauffele and Harris English - who sit at level par.

On his own in seventh place is Rory McIlroy of Northern Ireland, who is now one over par after a two-under round of 68.

American Patrick Reed, who led at the halfway point of the tournament, endured a torrid day on the challenging course, carding a seven-over-par round of 77, to drop him into a tie for 11th place.

Reed's front nine featured three birdies and two bogeys meaning he went out in 34.

On the back nine things went wrong for Reed as he dropped eight shots to return in 43.

He made six bogeys, including at the last two holes, as well as a double bogey on the 11th as he collapsed spectacularly to put himself in a position where he is unlikely to contend going into the last day.

When the Winged Foot course last hosted the tournament in 2006, Australian Geoff Ogilvy won with a final score of five over par.

The final round is scheduled to take place tomorrow.