The Mexican journeyman discussed his new club's upcoming clash with Barcelona, as well as his nation's chances of qualifying for World Cup 2014.
The Mexican forward arrived in Spain after spending the past year in his native country following spells in Greece, MLS, Ukraine and England. Castillo is excited to take on the Blaugrana on Saturday and insists his club is not intimidated by the likes of Lionel Messi, Andres Iniesta and Co.
"Barcelona do not scare us," the 29-year-old told Goal. "Neither me nor the team. Battling teams like [Barca] motivate me even more. We need to get out and give the maximum effort, happy with the effort we put out."
Castillo spent seven seasons with Olympiakos before becoming somewhat of a journeyman, but is thrilled to have found a home with Vallecano.
"I am very happy to be in this city and in the team," he said. "The truth is that I made a very good decision to come here. I’m with a good group and I hope everything goes well from here on out, playing and scoring goals.
"I started very young at Olympiakos and learned a lot, but Shakhtar Donetsk was my big mistake and had to request to leave. I thank God I have overcome some of the obstacles I have faced and now I’m happy to be here."
The forward has not taken part in any of Mexico’s qualifying matches for the 2014 World Cup, but has been paying close attention as a spectator, saying it is vital that the nation qualify for the tournament.
"It would be bad for all of Mexico," he mused. "It is such a big event for the country, the people and the sponsors. [Missing out on the tournament] cannot happen, it is impossible. To not be in the World Cup would be a heavy blow for Mexican football. But the truth is that it can happen.
"Mexico have to fight to death in the next game, because they have no choice, and I think they will achieve their goal because they have great players and a new coach who will surely help change things. Hopefully the team will improve."
Mexico currently sits fifth in CONCACAF qualifying, and whether it reaches the finals in Brazil next summer is no longer solely in its hands.