The sucker punch, Cowardly or Smart fighting?

Cosytoasty
So i watched a fight earlier in a bar. A lone guy was moving in on a couple of girls in a group of friends, one of the men in that group took exception to this and asked him to go away (several times). The newcomer refused and got right up into his face, group protector put his drink down slowly and then dropped him in one hit.

My colleagues were split on it, some of them think it's cowardly others think it's justified and actually a smart way to fight, "It's not a boxing match, it's a fight".

What do you think?
Smart move (fighting to win)
Cowardly (I let the other man swing first)
Select gender and age to cast your vote:
The sucker punch, Cowardly or Smart fighting?
23 Opinion