Craig Levein's men must match or better the Czech Republic's result against Lithuania to have any chance of progressing to the Championships in the Ukraine and Poland next year.
Scotland are rated as the underdogs for tomorrow's match in Alicante but captain Fletcher has revealed that Levein's squad are full of belief.
"To speak about getting a point, although it might be a great result, might be irrelevant; it might not be enough," Fletcher told reporters. "We know going into the Spain game that it is in our hands and if we win we will finish in second place.
"But we might lose and be in second place and we might draw and not be in second place so it's going to be one of those nights.
"We can only try to do our best and we will give it everything and although people are maybe writing us off, while there is still a chance we will keep believing."
Scotland moved up to second in their qualifying group on Saturday evening with a 1-0 victory over Liechtenstein.