With a win, Butler (24-7, 11-5) will face fourth-seeded La Salle (21-8, 11-5), which could use another impressive victory to ensure the Explorers aren't sweating on Selection Sunday.
The Argentina star has scored eight times in Barcelona's first five La Liga matches of 2013, including four against Osasuna in a 5-1 win on January 27.
No team has overcome a three-goal deficit from the first leg in a Champions League knockout stage matchup since Deportivo La Coruna beat AC Milan 4-0 in the 2003-04 quarterfinals for a 5-4 aggregate win.