 Shortly after Colo-Colo appointed Américo Gallego as club's new coach.On 2 March 2011, Castillo played in Gallego's first match in the bench that Colo-Colo won 4–2 to Venezuelan Deportivo Táchira for the Libertadores where receive a twice of the Chilean Julio Gutiérrez.The club continued his rise after winning 2–1 to Unión Española at Santa Laura on 6 March where his performance was marred after receiving a 20-yard goal of Kevin Harbottle who chipped Castillo.