Javi Guerra put Valladolid ahead in the 12th minute at their Jose Zorrilla stadium before their best player, German winger Patrick Ebert, limped off with an apparent muscle strain and Oscar made it 2-0 16 minutes from time.
Valladolid now lie in 10th position while Zaragoza are 13th.
Real Zaragoza had 47.4% of the possession during the match.
Los Blanquillos had 12 shots, including two on target.
The six attempts by Helder Postiga were the most of any Real Zaragoza player.
Tarsi was brought on to replace Apoño in the 28th minute when the latter went down with an injury.