Third seed Andujar defeated Italy's Flavio Cipolla 6-3 7-5 while seventh seed Albert Ramos took care of Russia's Igor Andreev 6-3 7-6(7)
While it will be a fifth ATP final for Andujar (who has a 1-3 record in deciders) it will be the first final for Ramos.
"It was a difficult and very close match today. I had to run a lot and he was hitting the ball so hard," Ramos told the ATP website.
"It is my first ATP World Tour Final. I'm very happy and excited about the match."