When the third round ended, Rose had a 6-under 64 -- six birdies on the front, all pars on the back -- for a one-shot lead over Schauffele and Rory McIlroy going into the final round at Aronimink, a course so soft from rain than the average score from 69 players over three rounds was 67.5
At stake is chance for Rose to reach No. 1 in the world for the first time with his third title in the Philadelphia area, including his U.S. Open at Merion five years ago.
Jordan Spieth was projected to fall just outside the top 30 in the FedEx Cup, which would mean missing the Tour Championship and getting some form of penalty from the PGA Tour because of his schedule. He would have one more day to change that.
The question lingering amid the clouds: Would there be another round?
Rose tried not to think about it.
Starting times were moved up to 7 a.m. Sunday with hopes that the heavy rain stays away, and that the final round can get in. The forecast has a small window Monday morning if needed. If the rain is relentless, there's a chance of a 54-hole tournament, which has happened only once in the 11 years of the FedEx Cup playoffs.
Rose was at 17-under 193, and 13 players were within five shots of the lead. That included Tiger Woods, who missed only two greens in regulation, kept a clean card, shot 66 and let a good round get away. That's how much of a pushover Aronimink has been this week.
McIlroy had a 63 with a double bogey, though he bounced back from that on the very next hole with a 3-wood that barely moved forward when it hit the green, caught the slope of a ridge and left a short eagle putt he converted.
"I'll be ready to play. I'll be ready to go. I hope we play," McIlroy said. "I feel like my game is in good shape and I'd love to get another crack at it out there and have a chance to take the lead. Maybe that chance won't happen until Monday if it goes to that and the good thing is we don't have a tournament next week."
Rose made four straight birdies early on the front nine to quickly erase a two-shot deficit to Schauffele, and he finished the front nine birdie-birdie for a 29.
Schauffele, hopeful that a victory will give U.S. captain Jim Furyk reason to pick him for the Ryder Cup, stayed with Rose the whole way until his lone bogey on the 18th for a 67.
"Still have a good chance tomorrow," Schauffele said.
Spieth salvaged his round late again for a 66. He has never missed the Tour Championship, and he likely would face some form of penalty for not having added a new tournament to his schedule without competing in at least 25 events. He needs to be at East Lake to reach 25.
Keegan Bradley made two tough pars for a 66 and narrowly edged past Spieth for the 30th spot. For someone like Bradley, getting to the Tour Championship would get him into all four majors next year.
Scoring was the lowest it has been all week at 67.17. Only six players from the 69-man field were over par, and there was a 62 for the third straight round. Tommy Fleetwood has two of them, Friday and Saturday. After opening with a 71, Fleetwood goes into the final round just two shots behind.
So does Rickie Fowler, despite a bogey on the final hole for a 65. Fowler played in the final group at Aronimink in 2011 when it held the AT&T National, though he faded to a tie for 13th. He is trying to win for the first this year.
For Woods, it was another lost opportunity, even though he remains in the mix. He opened with two straight birdies and the crowd was on his side, loud as ever. He followed with 11 straight pars, even though he had chances from 15 feet and closer.
"I hit the ball well enough to shoot a low score and I got off to a quick start," Woods said. "I was looking up on the board and everyone seemed like they were 3 under through eight, 5 under through 9. I was only 2-under par. I wasn't doing much."
It was the 17th time Woods had a 54-hole score of 198 or lower. The previous 16 times he was either leading or tied for second. At Aronimink, he was tied for 11th.