Luke Donald's hopes of winning the PGA Tour money title suffered as Webb Simpson finished second in the McGladrey Classic at Georgia.
Simpson has a $363,029 lead over Donald and the Englishman will have to finish first or second in the final event next week to keep his hopes alive.
Ben Crane won the event after a play-off against Simpson.
He came from seven shots back with 11 to play to force a play-off and won when Simpson a short putt.
Crane ended with a seven-under round of 63 after hitting seven birdies in a stunning finale to reel in Simpson.
"Finishing second is going to make it a lot harder for Luke," said the 26-year-old Simpson, who is in only his third full season as a professional.
"But I'm sure he's going to play well. He's played well almost every week this year. I still wouldn't be surprised if I have a little work to do.
"He's had a week off, so I'm sure he's rested and ready. It would be nice to run away with it, but it wouldn't surprise me if it's going to be pretty close."
The final PGA Tour event is the Children's Miracle Network Hospitals Classic in Florida, starting on Thursday.
Donald is over £1m ahead of second-placed Rory McIlroy on Europe's Race to Dubai, but that battle still has two months to run.