Amore Magazine

For a little guy, he can pack some power. Earlier this week we told you about how Shia LaBeouf got into a fight outside a bar in Vancouver.

Now we are learning details of the fight from TMZ - who claim that Shia threatened the guy who punched him with a knife.

TMZ spoke with Shea Carter ... the man who restrained Shia after the fight ... who tells us he noticed the actor inside the Cinema Public House bar BEFORE the melee. Carter says LaBeouf had been drunkenly swaying into several patrons ... including one man who calmly warned Shia, "Hey man, watch out."

Carter says Shia replied, "Oh yea? Or what? What are you going to do about it?"  That's when the two decided to take things outside ... and the guy beat Shia down to the ground.

Afterward, Carter -- a local hip hop artist and  bar regular -- tried to stop Shia from getting back inside, but LaBeouf got aggressive, spouting, "Well what if I grabbed my knife on you?"

Wow!! Someone is an aggressive drunk!

[TMZ]