The 20-year-old right-back fractured a bone in the joint between his left foot and ankle during the 3-0 victory at Montjuic, and will undergo surgery in Barcelona on Tuesday.
"It has come at a bad time for me because I was playing regularly," said Bertrán, who has been introduced into the Espanyol first team this season under new coach Javier Clemente. "
I just have to be patient and get back to fitness as soon as possible."
The win against Santander left second-bottom Espanyol within three points of safety in the Spanish Primera División table.
©UEFA.com 1998-2015. All rights reserved.