The title match will bring together the ninth and 15th-seeded players in the final tournament prior to the start of the U.S. Open.
Melzer, the ninth seed, earned a shot at the crown by defeating Sam Querrey 6-2, 4-6, 6-3. Monfils ousted Alexandr Dogopolov 7-6 (11-9), 6-3.
Both the finalists have won four tournaments in their career.
They have met on four occasions with Monfils having won all of those matches. They faced each other earlier this year for the first time in four seasons, that match having been played in Munich.