Fair Territory Rules: First Baseman with One Foot Foul

Question
If the 1st baseman is holding a runner on 1st base, is he considered to be in fair territory if he has one foot in foul territory? Or does he have to have BOTH feet in fair territory to be considered "in fair territory"?

Answer
Martin,

If that one foot is completely outside of fair territory, the player is not considered to be in fair territory.  We judge it to where his foot is, and it must be completely outside of fair territory.

Remember that this applies to when the ball is put in play(4.03).  Some umpires will give leeway to the fielder if they are trying to make an attempt to stay in fair territory.  However, according to the rules, both feet must remain in fair territory.

-Martin Hoover