Complex sentence: In December 2007, Palacio participated in the 2007 FIFA Club World Cup, playing in Boca Juniors' 1--0 victory over Tunisian club Étoile du Sahel on 12 December.
Split into simpler sentences: In December 2007, Palacio participated in the 2007 FIFA Club World Cup. Palacio had played in Boca's 1--0 win against Tunisian club Étoile du Sahel on 12 December.