 Already signed with Strikeforce, and following his own back-to-back wins outside the organization, Santiago was called back to the UFC to take on Gunnar Nelson in a welterweight bout on February 16, 2013 at , replacing an injured Justin Edwards.Santiago lost the fight via unanimous decision and was subsequently released from the promotion for the third time.Santiago signed with World Series of Fighting in 2013 and made his promotional debut on August 10, 2013 against Gerald Harris at .