"Before Combat Begins"

[felwred]

Ran into a strange rules question that is undefined. We're playing a game of original munchkin. Player X kicks the door and encounters a monster where it has the phrase "before combat begins, discard an item in play." Player X has no items out so no problem there. Being an evil bastard, I see the opportunity to play the potion of Transferral to move the combat from player X to player Y (because player Y has the kneepads of allure as his only item and it was an easy way to get rid of them). Alas, the argument ensues...

When the transferral potion was played, Player Y had to fight the monster but argued that the "before combat" didn't apply since the "before combat" was with the other player and he only inherited a combat and wouldn't therein lose his item.

So - it raises the question. When is "before combat?" It has to be after the door is kicked otherwise no combat is possible. However, when you kick the door - the effects of the door are immediate (you can't change classes, equip or unequip items, etc after drawing). In this case, is player Y exposed to the "before combat" effects and, if so, why?

Thanks!

Fred