The Spanish outfit have also been drawn to face Manchester United in the last-16 stage of the Champions League, with the first leg to be held at the Estadio Ramon in February.
Castro has accepted that Sevilla are in need of some fresh blood, and the Spaniard has promised that money is in place to improve the squad next month.
"The money available to this club will be used to fund the players who will be on the pitch," Marca quotes Castro as saying.
"We will look to strengthen the squad with signings next month especially at the request of the coach (Eduardo Berizzo) and we have shown we are never afraid to strengthen. It is clear our squad has deficiencies and we must address these, and I can ensure everyone we will work hard on this."
Sevilla will look to return to winning ways in La Liga when they host Levante on Friday night.