Sergiy Stakhovsky faltered early but recovered to down Denis Istomin 3-6 6-3 6-4 and claim the ATP Pilot Pen in New Haven on Saturday.
The ninth-seed Ukrainian rallied from one set down to claim his fourth ATP Tour title and his second of the season in one hour and 42 minutes.
Istomin breezed through the first set in his first career final, protecting his serve and breaking Stakhovsky in the second game to take the set in 32 minutes.
But the Ukrainian broke back in the second set, taking Istomin's first game and holding his own to set up a third-set decider.
Stakhovsky and Istomin held serve to 2-2 in the final set, but Istomin gave up a break point in the fifth game which Stakhovsky duly capitalised on.
The Ukrainian did not drop a point in his next two games to reach 5-4, finishing the deciding game at 40-30 with an emphatic overhead smash.
Earlier on Saturday, Wimbledon finalists Robert Lindstedt and Horia Tecau took out the men's doubles final with a comfortable 6-4 7-5 victory over Rohan Bopanna and Aisam-Ul-Haq Qureshi.
The Swedish-Romanian duo overcame Bopanna and Qureshi for the third time this year to lift their fourth trophy of the season, having already triumphed in Casablanca, s-Hertogenbosch and Bastad.