It is impossible to hit this man in his face.
The guys from howtofightnow went on the streets to search for people that wanted to throw some punches. The task was easy, the match holds two people and only one of them is allowed to throw punches. The other one is only allowed to dodge them, he is not allowed to hit them back.
Now just take a look at the howtofightnow video below, on how this technique will allow you to win random street fights, just do note that it is better to prevent assaults but if it is required do not be afraid to defend yourself.