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 "2008 Supercopa de España"): It was contested by Valencia, who were Spanish Cup winners in 2007–08, and Real Madrid, who won the 2007–08 La Liga.
Relevant evidence: No