|Tour Championship third-round leaderboard (US unless stated)|
|-19 D Johnson; -14 X Schauffele, J Thomas; -13 J Rahm (Spa); -12 C Morikawa; -10 D Berger, S Im (Kor); -9 S Scheffler; -8 R McIlroy (NI), B Todd, T Hatton (Eng)|
World number one Dustin Johnson has a five-stroke lead heading into Monday's final round of the PGA Tour's season-ending Tour Championship at East Lake.
The in-form American, 36, was a shot clear of Sungjae Im overnight but shot a six-under 64 in the third round that included seven birdies.
Xander Schauffele shot 67 to sit tied for second with fellow American Justin Thomas, who carded a four-under 66.
Spain's world number two Jon Rahm also shot a 66 to lie six behind.
This is the fourth consecutive event Johnson has held at least a share of the lead after three rounds.
He was edged out by Collin Morikawa in the US PGA Championship and by Rahm in extra holes last week at Olympia Fields but a fortnight ago turned one of the 54-hole leads into an 11-shot win at TPC Boston.
Johnson began the week on 10 under as the Tour Championship's top-ranked player and following two steady rounds left him 13 under, his Sunday 64 has put him within touching distance of the FedEx Cup title.
The former US Open champion is seeking to claim the $15m jackpot for the first time having squandered an opportunity to win it four years ago when he shot a final-round 73.
"To be the FedEx Cup champion is something that I want to do," Johnson said. "It's something I want on my resume when I quit playing golf."
Northern Ireland's Rory McIlroy shot level par to stay on eight under, 11 shots off the lead - as is England's Tyrell Hatton after a one-over 71.
Daniel Berger matched Johnson's 64 to climb into the top 10, two shots behind US PGA winner Collin Morikawa who is in fifth after a 67.
How the Tour Championship works
Players at the event are handicapped based on FedEx Cup points earned during the season and the top 30 in the rankings contend the Tour Championship.
The top-ranked player begins the 72-hole tournament on 10 under par, while the second seed starts on eight under.
The third seed tees off at seven under and so on down to the fifth seed at five under. Seeds 6-10 begin at −4; seeds 11-15 begin at −3; and so on, down to seeds 26-30, who will start at level par.