Patrick Cantlay remains the man to catch in pursuit of the 15million US dollar (£10.9million) first prize at the season-ending Tour Championship, despite the concerted efforts of US Open champion Jon Rahm.
Cantlay added a second round of 66 to his opening 67 for a halfway total of 17 under par, the FedEx Cup leader having started the week on 10 under thanks to the controversial handicap system adopted in 2019.
Rahm began four shots behind Cantlay but reduced his deficit to a single shot thanks to consecutive rounds of 65 at East Lake, with Bryson DeChambeau a further five strokes back.
A previously low-key event finally sparked into life on the back nine on Friday as Rahm got to within a shot of the lead with a birdie on the 12th, only for Cantlay to then spin his approach to the next to within millimetres of the hole as Rahm came up short of the green.
Cantlay tapped in to seemingly restore his two-shot advantage, but Rahm had other ideas and holed from 35 feet for a matching birdie.
Rahm did well to drop just one shot following a wild tee shot on the 14th and birdies on the 16th and 17th took him briefly into a tie for the lead, only for Cantlay to follow him in from 15 feet on the 17th.
It was a similar story on the last as a superb bunker shot left Rahm with a tap-in birdie before Cantlay got up and down from the edge of the green to take a one-shot lead into the weekend.
Rory McIlroy is nine shots off the lead on eight under par after recovering from playing his first four holes in two over par to return a 66, the two-time FedEx Cup winner finishing in style with three straight birdies.
"I got off to a poor start and then got it going there on the back nine and just kept hitting good iron shots pretty close and converting a few of them," McIlroy said.
"And then I finished with a flourish. I birdied those last three holes and played those really well.
"I thought the pins today were pretty tricky because even if you hit the ball close, you still had big breaking putts, or if you're on the wrong side of the hole, it's still tricky.
"But to be two over through four and play the last 14 in six under was a really good effort to at least just keep myself in the tournament.
"I had a really good week last week and I know how to play this golf course. I've played it well before and shot 32 on the front nine yesterday and 30 on the back nine today so try to put those two scores together tomorrow and then I'd really have a good chance going into Sunday."
Three-time major winner Jordan Spieth is alongside McIlroy on eight under and revealed afterwards that he and his wife Annie are expecting their first child in November.
"It's old news for me but, yeah, eventually Annie was going to show and people were going to know," Spieth said.
"But, yeah, very excited. She feels great, that's the number one priority and everything's going smoothly."
