American qualifier Jamie Hampton will play her first career final on Saturday when she faces Russia's Elena Vesnina in the final of the Eastbourne International on Saturday.
The 41st-ranked Hampton earned her place with a 6-7 (8/10) 7-5, 6-3 upset of former world number one Caroline Wozniacki on Friday, while Vesnina followed up her ouster of China's second seed Li Na in the quarter-finals by crushing Belgian Yanina Wickmayer 6-2, 6-0 in just 51 minutes.
The men's final was also set with second seed Gilles Simon to take on Spain's Feliciano Lopez.
Simon beat 2011 champion Andreas Seppi, the Italian seventh seed, 6-4, 6-3, while Lopez, a former Wimbledon quarter-finalist, defeated Croatian Ivan Dodig 7-6 (7/3), 6-1.
"To be in the finals is a great feeling, it's good for me, for my game, for my confidence for the rest of the year," said Lopez.
"I'm very happy with my performance, and hopefully I can keep playing like this until the end of the year so I can improve my ranking again."
Simon will be appearing in his first career grass court final, the 14th of his career.
A winner of ten trophies, Simon is the sixth Frenchmen to reach the final here.
Earlier, the Hampton-Wozniacki clash took nearly three hours but could have ended much earlier had fifth seed Wozniacki managed to complete a straight-sets win.
As it was, the Dane was made to pay the price for missed opportunities by her surprise opponent in their first meeting.
"Obviously I would have loved to have won today, it would have been worth it to be out there for three hours," said Wozniacki.
"Actually we played a very good match. The wind that was there, it was so difficult. But I had my chances. I didn't take them, and, she played very well, I have to say.
"Overall I'm feeling good, I feel happy to be on grass. I feel like my game is where I want it to be. Hopefully at Wimbledon I'll do well."
The match was played in blustery conditions on the English south coast after several days of sunshine and atypical calm weather.
Hampton squandered five set points in the opening set to give the momentum to her opponent, but Wozniacki was unable to serve out the second set leading 5-4 after winning the first in a tiebreaker and came up short in the third.
Hampton, 23, will move into position as US number three behind Serena Williams and Sloane Stephens after the best week of her career.
Hampton was the first American woman since Jennifer Capriati a decade ago to play the semis at Devonshire park and is the first qualifier on the WTA to reach a final this season. The last American to win here was Chanda Rubin in 2003.
Hampton upset Wozniacki while playing in only her third career grass event and will compete at Wimbledon next week for only the second time after reaching the second round a year ago.
Wozniacki was denied a chance at her second career grass court title after winning Eastbourne in 2009.
Vesnina will aim for her second career trophy after making a breakthrough for the Hobart honours in January. The Russian stands 1-7 in career finals.