Things started badly for Rayo when Jordi Amat inadvertently put Grandada ahead in the 24th minute, directing Allan Nyom's cross past his own goal keeper. In his defense, there really wasn't much he could as he was under heavy pressure from Ighalo on the play.
Rayo actually fought back well after the goal, coming close a couple times. Medina Piti had a great chance that he fired just over the crossbar and Granada goalkeeper Fernandez Roberto made some fantastic saves to keep his side in the lead.
Rayo responded well to going behind and could have been level before the break as Medina Piti fired just over and Fernandez Roberto made a smart stop to turn over Vasquez's header from close range.
The Granada keeper made an even better stop to keep out Triguero Tito's powerful headed effort just after half-time, but Rayo's best chance of the afternoon arrived 25 minutes from time when a Casado cross from the left was deflected perfectly into the path of Lass only for the winger to screw his shot off target.
Recio put the match away in the 80th minute with a drive form distance that beat Rubén and ended Rayo's hopes of salvaging any points on the day.
Rayo were missing Leo Baptistao (injury) and Alejandro Dominguez (suspension) and it showed as they lacked any real edge to their attack.