Jason Day shot three under on the opening eight holes of the third round before rain washed away more play at the Zurich Classic in New Orleans.
With no-one able to complete their third round on the final scheduled day of play and more inclement weather forecast, organisers are now hoping for a 54-hole tournament to be squeezed in before rain reappears on Monday (Tuesday AEST).
"The rain just won't quit," PGA Tour rules official Steve Carman said.
"Obviously we would like to play 72 holes but that's looking more unlikely. So we're concentrating on the 54-hole finish."
Beginning on Sunday (Monday AEST) five shots off the pace at seven under, Day picked up two strokes on joint-leaders Brian Stuard of the United States and Venezuela's Jhonattan Vegas, who are each 13 under after five holes in their third round.
The world No.1 is in a five-way tie for fifth, two shots behind American Bobby Wyatt and one from Jamie Lovemark.
The Australian birdied the third, fifth, seventh and eighth holes, but shot one over on the par-four sixth.
Fellow Australians Stuart Appleby (through 13) and John Senden (through eight) are one shot further back in a four-way tie for 10th, while Ryan Ruffels is in a 10-way tie for 14th at eight under.
There is likely to be a three hour window for play on Monday morning (Tuesday AEST), however organisers are still concerned that might not be enough to complete the third round.
"Once it stops raining we're going to give it some time to drain and warm up time," Carman said.
"Then it would be an hour, hour-and-a-half maybe until we were able to get back out there."