Profiting from an assist from Marc Gual, the Spaniard placed the ball past goalkeeper Andero Cantero.
In a fixture short of plenty of scoring chances, Alcorcon took the lead into the half-time break.
Not willing to go down without a fight, the hosts put up an improved showing in the second half - and that yielded a positive result when they levelled the scores in the 49th minute.
Thanks to an assist from Jose Angel Carrillo, Cristian Herrera profited from shambolic defending from Juan Antonio Anquela’s side to slot the ball past goalkeeper Daniel Jimenez.
Ojeda completed his brace in the 72nd minute after converting from a rebound from his missed penalty.