Darren Clarke posted a disappointing final round of four-over-par 74 to fall down the field at The McGladrey Classic in Georgia.
The Northern Ireland player carded five bogeys during his closing 18 holes at Sea Island, with just a solitary birdie four at the par-five 15th.
The 2011 Open champion ended the tournament on four over in a tie for 65th position.
American Chris Kirk shot a 66 to win the tournament on 14 under.
South African Tim Clark fired a 62 to finish in joint second place on 13 under, along with Briny Baird who signed for a 67.
Clarke marked his return to the PGA Tour with a 69 on Thursday and followed that up with a 70 on Friday and a third-round 71 on Saturday.
Clarke showed a return to form last month when he tied for second place at the Nanshan China Masters.
The former Open champion is making his comeback as a full-time member of the PGA Tour this week after a seven-year absence, admitting it almost feels like a fresh start.
The 45-year-old, who lifted the Claret Jug at Royal St George's two years ago, last completed a proper season on the United States circuit in 2006 - the year his wife Heather died of cancer.
After making 10 starts on American soil, five of which were in majors or World Golf Championship events, the following year his appearances understandably tailed off as he wanted to be closer to home and his two sons.
His appearances in the States did not total double figures and have not since, but he has now decided the time is right to take up the full membership he is entitled to under his exemption for winning the Open Championship.
"I've almost had enough of the long hauls all over Asia and all that sort of stuff," said Clarke, who has not won an event since victory at Sandwich and has fallen to 283rd in the world rankings.
"Europe is my home turf but it's a great opportunity to come over here and play.
"I just want to go out and enjoy myself. I've travelled all over the world for a long time and I've had a great time doing it. It's almost like starting over.
"It will be difficult (playing both tours) but it is something I will try to do," he told PGATour.com.
Clarke will also play next week's OHL Classic in Mexico before returning for the AT&T Pebble Beach National Pro-Am and Northern Trust Open in February and the entire Florida swing in March.