Females are much better than males at projecting their emotions via body language and facial expression.
[And I'm not talking about Robert De Nero here, just your average guy on the street.]
Stare downs between male boxers before a big fight can very intense, but the tension there comes from the crowd, and the knowledge that this a BIG fight, with people all over world watching and waiting to see what's going to happen. Otherwise, if you get two guys going eyeball to eyeball before a fight, the reaction of most people is going to be - "Come on fellas, stop messing about and get on with it!".
Put two girls in the same situation though, and you have drama and tension the instant their eyes meet.