Duckworth, who is one of nine men among a 15-strong Australian contingent at the year's final grand slam in New York, suffered an injury to his right leg in Saturday's semi-final in North Carolina.
His withdrawal handed victory to Arthur Fery, who became the first British player to reach the final of the Winston-Salem Open.
The 24-year-old Briton had won the first set 6-4 and was leading 2-1 in the second when Duckworth, who had taken a medical timeout after the first set, was forced to withdraw 59 minutes into the match.
"I am really happy to be in the final," Fery told atptour.com after reaching his first ATP Tour final
"Not the way I wanted it to end at all. I hope James will get well soon and rest up for next week, but I am very happy to be through."
The win will lift Fery to a career-high No.33 in the world tennis rankings heading into the US Open.
In the final, Fery will face Peruvian Ignacio Buse, who beat Frenchman Benjamin Bonzi 6-2 4-6 6-1 in the other semi-final.
If he recovers in time to take his place at Flushing Meadows, 34-year-old Duckworth will meet Italy's Matteo Arnaldi, the 30th seed, in the first round.
- with AAP
8°C