Negredo, who struck from the spot, said at the final whistle: "The important thing is that we do not settle on this result. We must continue this form for the rest of the season.
"We were very serious and organised. The result was correct, we deserved it."
Real Madrid midfielder and Negredo's former Castilla teammate Javier Balboa said: "Things have worked out well for Negredo since he left Madrid and I'm happy for him. Almeria lifted their game and deserved the points."