Fourth seed Tommy Haas reached his first final in Washington at the ATP/WTA hardcourt event on Saturday on his seventh attempt with a 6-3, 7-5 defeat of top seed Mardy Fish.
Haas, aged 34 and ranked 36th in the world after starting the season on 205th due to hip and elbow surgeries in recent years, will be aiming for the 14th title of his career.
The German who stood second on the ATP in 2002, will face either second seed Alexandr Dolgopolov or Sam Querrey, winner in Los Angeles last weekend.
The women's final will pit Russian top seed Anastasia Pavlyuchenkova against Magdalena Rybarikova of Slovakia.
Haas will be playing his third final from his last five events.
"To finally reach the final on my seventh time here is crazy," said Haas, who did not commit an unforced error and lost only two points in serve in the first set.
"Who would have thought to have done that at my age. It means a lot to me, to be in this final is a great feeling."
Haas dominated in the opening set but got some stiff resistance from Fish in the second. The American forced Haas to save a pair of break points in the second game of the set before the pair settled back into their battle on serve.
The German struck after saving a set point in the tenth game as he won a 19-point exchange to hold serve.
Haas then took advantage with a break a game later in which Fish saved two break points with aces but double-faulted into a third, which Haas converted for 6-5.
Haas served it out a game later to end in 93 minutes with 21 winners and just seven unforced errors.
"That doesn't happen very often - especially with my game," said the 16-year ATP veteran who is into his 24th final.
"I knew I had to come out aggressive," said Haas. "Mardy is a tough player who is playing some of his best tennis now. He's one of the best on the hardcourt and he's been playing unbelievable this week.
Fish was ten months removed from his last semi in Tokyo in October and did not play in the Olympics by design after coming through an accelerated heartbeat health scare during the spring.