He faces fourth-seeded Fabio Fognini of Italy in the final. The 2013 finalist beat Gastao Elias of Portugal 6-3, 6-3.
Martin and Berlocq played each other in Umag two years ago, when the Argentine won in the first round.
After an unpredictable first set Saturday - with six breaks in the first eight games - Berlocq led 4-2 in the second set before the 124th-ranked Martin won four straight games to close the match.
Fognini did not face a single break point against Elias.