Depends on the location of the fight. Crocodilians are biologically designed to attack upwards in more shallow locations, hence the location and structure of their eyes and sensory organs. Great whites also attack from below, but from much deeper waters and are the more adaptive aquatic hunter... both have sensory organs in and around their mouths that allow them to track and attack prey even when their vision is obstructed, of which both suffer from loss of vision while their mouths are open... the other issue with crocodilians is that they are also designed for life on land (however infrequent) making them not the greatest in the water and definitely not on land. A shark is built solely for one habitat and while in it, a crocodile doesn't stand a chance.