Extracted from Charles Smith-Jones excellent study of muntjac:
"The bucks will engage in a shoving match using antlers, pedicles and foreheads, each pushing and twisting in an attempt to throw their opponent off balance. The buck that succeeds in doing this will then attempt to slash his adversary with his tusks, aiming for face, ears or neck...or rump, in the case of a fleeing opponent."
This tallies with what I have seen of muntjac - mostly there's a lot of 'foreplay' as they opponents stamp and stare. Only if this fails will you get physical confrontation but I've not seen anything other than the above.
willi_gunn