Question:  The 2008–09 Copa del Rey final was held at a football stadium which as a seating capacity of what?
Sentence (from "2014 Copa del Rey Final"): The match was an "El Clásico" between Real Madrid and Barcelona on 16 April 2014 at Mestalla in Valencia, making it the seventh such Copa del Rey final (the last one was also played at the Mestalla on 20 April 2011).
Relevant evidence: No