The world and European champions just need a point to be sure of their spot at the World Cup next summer, but the former Sevilla forward has warned against complacency.
"It's hard with the national team. There are many good players, that's why when we come on the pitch we give it our all, and there are times when it goes well and others when it doesn't," he told reporters at a press conference.
"The truth is that I've been lucky in the last matches, you need to make the most of it. It will be difficult, they will be at the back, but the truth is that the matches are getting tougher, but we don't let them get away."
Negredo, 28, has scored nine goals in 18 games for Spain.