are you talking street fight or a competition spar? in a street fight and that happened i wud push off of my back leg forcing myself at him, bend the knee of the leg to bring myself closer to him and grab his shoulders and nut him, i know it seems a bit complicated but its a move by move break down and if u think about it, it wudnt be to hard to do, but if its competition i wud risk a jumping mawashi, and i know u r asking a "what if" cos anything can happen, but like mostly everyones sed, just try not to get into that situation