A hit ball that would have landed foul beyond first base, but was redirected by the defender and lands fair. The ball never touched the ground until after it was deflected by the defender. Is that a fair or foul ball?
I'm going to assume you're asking about MLB rules. There, a fair ball is defined as:
A FAIR BALL is a batted ball that settles on fair ground between home and first base, or between home and third base, or that is on or over fair territory when bounding to the outfield past first or third base, or that touches first, second or third base, or that first falls on fair territory on or beyond first base or third base, or that, while on or over fair territory touches the person of an umpire or player, or that, while over fair territory, passes out of the playing field in flight.
So in this case it's not where the ball was going, or where it landed. It's not even where the defender was standing. It's where the ball was touched by the defender.
- If the ball was over fair territory when touched, the ball is fair.
- If the ball was over foul territory when touched, the ball is foul.