By Lewis Gould

The fourth round of the BMW Championship was washed out at Aronimink in Newtown Square yesterday.

And they are trying again today.

Aronimink was already was saturated when a steady rain caused tiny streams and large puddles in the fairways, leaving the PGA Tour little choice but to wait until today to either play the final round or decide to cut short the third FedEx Cup playoff event to 54 holes.

‘‘We had a golf course we couldn’t play,’’ Slugger White, the tour’s vice president of competition, told the AP. ‘‘We’re shoveling sand against the tide.’’

Justin Rose was ahead by one shot, all because of one putt.

He was tied with Xander Schauffele on the 18th hole of the third round Saturday when Schauffele’s 8-foot par putt rimmed around the cup, giving him a bogey and Rose the lead.

Rose can go to No. 1 in the world for the first time in his career with a victory, making him the 22nd player to reach the top since the ranking began in 1986. He also would be the No. 2 seed behind Bryson DeChambeau among the top 30 who advance to the Tour Championship in two weeks, giving him a shot at the $10 million prize.

Keegan Bradley might be there, too, all because of one putt.

Bradley left his 50-foot birdie putt about 7 feet short on the 18th hole Saturday. He made that for par to finish the third round in sixth place, three shots out of the lead. That projects him to move up 22 spots into the 30th position in the FedEx Cup, which would bump out Jordan Spieth.

Still to be determined was whether another shot is hit — or enough of them.

‘‘We will do everything we can to play [Monday],’’ White said.

The forecast was for light, scattered showers this morning, with thunderstorms developing in the afternoon.

The hope was that the rain would be light enough to play, and the thunderstorms would be slow to develop.

The first tee time was scheduled for 7:30 a.m. The last group was to tee off at 8:50 a.m.