When describing a sudden physical attack, the phrase "sprung at" can be replaced with several different synonyms. These could include "lunged at," "attacked," "pounced on," "charged," or "rushed toward." Each of these options emphasizes the sudden, aggressive nature of the action being described, but also brings its own nuances and connotations. For example, "pounced on" could suggest a more animalistic attack, while "lunged at" could imply a more deliberate, targeted action. Regardless of which synonym you choose, the important thing is to convey the intensity and abruptness of the attack in question.