Don't underestimate the fighting capability of the individual knight.

I joined a similar discussion in another forum... Now the knights usually underwent a serious enough training, I still believe that the samurai trained more to perfect their skills with the bow. At the same time the usage of bow while riding is among the profficiencies of the japaneese elite warrior, and to stop a charging cavalry it's not necessary to aim at rider. In the japaneese army around the Middle Ages long yari (spears) were quite common and alongside naginata and nagamaki (under some conditions considered polearms) are devestating against mounted units. With the fact that a disciplined army of horse archers can indeed bring down a large amount of heavy cavalry (tested by the Mongols and Tatars) it's hard to say the knights will prevail while charging. Hard to believe as well that the samurai would be dumb enough to meet that charge.

"I don't think Samurai made much of a habit of going around the back..."

Disagree! The Art of War among many did teach some of the most ingenuine tacticians about finding a weak spot and using it. It's wrong to believe that the samurai always faced the opponent face-to-face. The battle at Sekigahara for once proves that this idealization of the samurai class is in fact denying some of the principles of warfare (the same people would insist that ninja are dressed in black, and yeilding a sword, run around slaughtering any enemy). Furthermore, a daimyo such as Takeda Shingen developped to a new stage the samurai cavalry, appearing out of nowhere, ambushing, making decoys, folding back then striking again - the way he defeated two of the finest leaders Oda Nobunaga and Tokugawa Ieyasu.

Now taking a look at the armor - samurai armor did indeed stop to some extent the katana blow. So some hits below the elbows were a sign of sword mastery. Tachi is designed for slashing primarily and here the same principle is applied - searching for loose points. A knight brought down from a charging horse would be severly damaged. Loose points can be found in most of the European armor plates and it would require too heavy of an equipment to tighten these dangerous spots which would turn a knight on foot in practically useless on foot.

Some knights, as the templars, would show excessive zeal on the battlefield, many of them fine swordsmen, though their phylosophy is the opposite of the one of the East. This might result in an even more interesting clash, yet in my opinion the zeal and the heavy armor would result in a greater fatigue.

I guess we'll never know. So as much as this topic is amusing it's still highly hippothetical.

the question is one on one(says if two met).. the samurai went around the back in a one on one dual?

Sorry, my mistake! Well a good warrior will consider the option, a moral one will go face to face following the tradition.

Those who betrayed the memory of taiko, show that morale is sometimes neglected. So there will be such that fit in the first category.

And still if the battle starts face to face (the opponent is given the proper chance to defend himself), a feint that leaves the warrior behind the opponent's back is quite possible, at least this is my opinion based on my knowledge of martial arts (particularly, moving to the side, positioning a bit to the back of the opponent and attack of the back side of the knee - could be a low kick).

the samurai will get pwn, if  the knight is on horse (as I would expect) the samurai will be impaled, french knights train on that all the time. If on the ground, Japanese sword is better but if the knight fight with a shield, then the samurai will be defeated since the knight is usually bigger, more armoured and powerful.

 The Japanese Samurai

 Samurai