Japan mistake.
Japan fighter souldn't have been a sumo fighter, but a practioner of ninjitsu. A practioner of this style would have killed every fighter there, including John claude's charater. The only possible reason why this kind of fighter wasn't chosen is 1. The director never heard of it. 2. The director felt that it would be introducing a too powerful of a fighter or because of the well known fact that practioners of ninjitsu don't like to participate in any kind of tornameant, unless chalanged. It would have benn right thou to have a practioner of ninjitsu as it's japan greatest martial art; and it would have been just amazing to to see a ninja going for peoples presure points, knocking them out this way, maybe even seeing the dim muak,of course the fights would be very short, no flashly moves.
Here's some videos of ninjitsu. I didn't post these video's so you know.
http://www.youtube.com/watch?v=tMOTWHnd9X0&feature=related
http://www.youtube.com/watch?v=ssd7NxaQHZQ&feature=related