 Ruiz began his professional career at 18, making his debut for Liga Deportiva Alajuelense on 30 November 2003 against Municipal Pérez Zeledón, in Costa Rica's top division.He formed a trio with 2 strikers, Rolando Fonseca and Froylán Ledezma, where he built a reputation as a goalscorer and a play maker.Ruiz scored his first goal on 23 December 2003 against Ramonense, netting twice against Fernando Patterson.