Under new manager Héctor Cúper, Mendieta had an even better year in 1999–2000. He helped Valencia beat Barcelona 4–3 on aggregate to win the Supercopa de España, and netted a career-best 13 goals as the "Che" finished third. However, the biggest triumph of the season was helping his team reach the final of the season's UEFA Champions League, a 0–3 loss to fellow league side Real Madrid; later, he was awarded the "European Midfielder of the Season" award.