Super Mario Bros./Walkthrough

Mini-Fiery Mario
If Super Mario touches Bowser and the hammer simultaneously, he will flicker as if he is about to revert to regular Mario. When Super Mario obtains a mushroom in the following stage, he will shrink into regular Mario. The next power-up he can get (assuming he is not hit first) will be a Fire Flower that changes his color and allows him to shoot fireballs while still small.