Complex sentence: He lost his WBC Light Heavyweight Title against Jean Pascal on 19 June 2009 and also lost a rematch against the same oponent on 11 December 2009 at the Bell Centre in Montreal.
Split into simpler sentences: He lost his most recent fight against Jean Pascal on 19 June 2009 for Diaconu's WBC Light Heavyweight Title. There is rematch between Diaconu and Pascal scheduled for 11 December 2009 at the Bell Centre in Montreal.