Question: What team won a two-leg Spanish football match played on 20 August and 23 August 1997, which one contestant won the 66th since its establishment, started on 31 August 1996 and finished on 23 June 1997?
Sentence (from "1997 Supercopa de España"): The contestants were FC Barcelona, who were Spanish Cup winners in 1996–97, and Real Madrid, who won the 1996–97 Spanish League.
Relevant evidence: No