What's your favorite movie duel?

When I say duel, I don't mean necessarily a fight set upon rules or common agreements, it can be a violet encounter in which all parts show their skills in fencing or shooting.

Personal favorites are Tyrone Power against Basil Rathbone in The Mark of Zorro (1940) and the masked theater sword fight in Scaramouche (1952), although the obvious mention would be Westley vs Iñigo Montoya in The Princess Bride.

Honorable mention: Lady Snowblood, as in, the whole movie.