Hmm, at 3m while he's sprinting, that's not a very big time window, so I'd say aiming anything other than a sawed-off shotgun is out of the question. Especially since he's apparently caught me by surprise.
I'm assuming "Do a barrel roll!" Would be a bad answer
I'd probably go for a big shoulder tackle or a swift LMG crosscheck to the chest. Something to knock him off balance - he can't pull off any of that dodgy crap when he's on his ass, unless we're dealing with a crab-walking operative... which at that point the situation would be pretty dire :unsure2: