I found a couple awesome video's of Whitetail bucks fighting on youtube. I thought I'd share them with you. The first one is the most awesome buck fight I've ever seen. Unreal the way these two bucks go after each other!
This second one is of two larger bucks fighting, but the picture quality is poor and the camerman was a ways away. Still a good fight though.
As you can see, some of these Whitetail buck fights get pretty down and dirty. Some even end in death. I've seen bucks spar, but never get into fights like these two video's show. It may just be a matter of time.
Notice how other bucks will come and butt in (no pun intended..lol) This is why rattling is so effective just before the rut and during the rut.