Spieth uses birdie run to grab lead at Northern Trust

The British Open champion seized control with three straight birdies from the 14th en route to a six-under 64 at Glen Oaks Club where he leads world number one Dustin Johnson (67) in the first of the PGA Tour's four lucrative FedExCup playoff events.

(Reuters)

Spieth, whose 64 tied the low round of the week, had four birdies on a front nine that he bookended with bogeys but once again dominated the back nine by shooting 31 a day after needing 30 shots to complete the same stretch.

"(This course is) pretty straightforward," Spieth told CBS Sports. "It's very much in front of you. I'm going to need to (drive it better) tomorrow to make it easier on myself."

Spieth, who held a share of the overnight lead with fellow Americans Johnson, Rickie Fowler (74) and Venezuela's Jhonattan Vegas (72), will now focus on trying to convert a 54-hole lead into victory for the 10th time in his last 11 outings.

Britain's Paul Casey (66), Spain's Jon Rahm (67), and Americans Patrick Reed (66) and Matt Kuchar (68) were five shots back of Spieth heading into the final round.

(Reporting by Frank Pingue in Toronto; Editing by Ian Ransom)