Britain's Paul Casey withdrew before the start of Saturday's third round of the McGladrey Classic at St. Simons Island in Georgia because of a stomach ailment, effectively costing him his PGA Tour card for next season.
The English world number 20 had entered the U.S. circuit's penultimate event of the year in 127th place on the money list, needing to break into the top 125 to secure full playing privileges for 2012.
Casey, who plays on both the PGA and European tours, is not scheduled to compete in the season-ending Disney Classic at Lake Buena Vista, Florida, next week.
An 11-times winner on the European Tour whose only PGA Tour victory came at the 2009 Houston Open, Casey has been hampered for much of this year by a sore right toe.
He has played with a plate in his right shoe and his toes taped since late May.