Kanepi lost her serve in the first game of the match but played solidly from there for a 6-4, 6-3 win over Ayumi Morita. She had a pair of breaks in each set, including Morita's final two games serving.
She'll meet a familiar opponent in the semifinals in fourth-seeded Carla Suarez Navarro who beat Monica Puig 6-2, 6-4 in her quarterfinal. Suarez Navarro, like Kanepi, had two breaks in each set.
Kanepi claimed a 3-6, 7-6 (8-6), 6-4 win in last year's Portugal Open final to improve to 2-1 lifetime against Suarez Navarro.
The other semifinal sends third-seeded Anastasia Pavlyuchenkova against Romina Oprandi in a career-first meeting.
Pavlyuchenkova was the only quarterfinal winner pushed to three sets as she defeated No. 7-seeded Elena Vesnina 6-3, 6-7 (3-7), 7-6 (7-3) in a 2-hour, 45-minute match. Oprandi, on the other hand, was on the court 63 minutes in dispatching Svetlana Kuznetsova 6-2, 6-2.