Patrick Reed edged into a one-stroke lead at the Northern Trust as Dustin Johnson and Jordan Spieth struggled during the third round on Saturday.

Reed and Abraham Ancer battled it out for top spot in the final holes of the round at Liberty National Golf Club.

The two traded places until Reed took the outright lead, moving to 14 under at the opening FedEx Cup play-offs event.

The American used five birdies to help counter a bogey on the par-four 15th hole and carded a four-under 67 on Saturday. It was one stroke off the 66s he carded in both the first and second rounds, but it was enough to gain some ground on Ancer and the rest of the field.

Ancer also had a few hiccups with bogeys on both the front and back nines, including the par-four 16th hole, as he carded a 68.

Johnson and Spieth were the top two overnight, but they fell back after shooting three-over 74s.

World number two Johnson is at nine under in a tie for 10th after carding four bogeys on his last six holes to be just one shot ahead of Spieth.

Brandt Snedeker fired the best round of the day – an eight-under 63 – to move into a tie for third place at 12 under with Jon Rahm (69).

Danny Willett, Justin Rose and Harold Varner III are tied for fifth at 11 under, while Louis Oosthuizen and Rory McIlroy make up a tie for eighth a shot further back.