Tommy Haas beat top seed Mardy Fish in the Citi Open semis in Washington DC on Saturday, while Magdalena Rybarikova won the women's final.
Haas knocked out Fish in straight sets at the William H.G. FitzGerald Tennis Center to progress through to the final, where he will face second seed Alexandr Dolgopolov.
German Haas, the fourth seed in Washington, reached his 24th ATP World Tour final with a 6-3 7-5 victory over America's world number 15 Fish.
The 34-year-old Haas saved all three break points he faced as he moved a step closer to winning his 14th career title.
Standing in his way is Ukrainian Dolgopolov, who completed a disappointing day for the United States with a 6-4 6-4 win over Fish's countryman Sam Querrey, the eighth seed.
Dolgopolov, 23, is seeking only his second career singles title in his second final appearance of the year, having lost to Andy Murray in the title match in Brisbane in January.
In the women's final, unseeded Slovakian Rybarikova capped her remarkable run in the tournament by thrashing top seed Anastasia Pavlyuchenkova of Russia 6-1 6-1 in just over an hour.
The unseeded Rybarikova, who beat second seed Chanelle Scheepers in the first round and knocked out third Sloane Stephens in the semi-finals, won five of the seven break points she fashioned while saving the only one Pavlyuchenkova had.
This is the third WTA singles title of the 23-year-old Rybarikova's career.
