A product of hometown CD Numancia's youth system, Mario first appeared with its first team during 2002–03's second division (two appearances), then played 34 matches scoring three goals in 2007–08, as the Soria team returned to La Liga after a three-year absence.
On August 31, 2008, making his top flight debut, Mario scored the only goal as Numancia shock defeated FC Barcelona at home. It would be his only in the campaign, as the club was immediately relegated back.
