What is the ruling when a ball called "infield fly" curves into foul territory?

When a ball is called an "infield fly" and then curves into foul territory, the correct ruling is that it becomes an ordinary foul ball, which means the batter is not out. The infield fly rule is designed to prevent the defense from taking undue advantage of the situation when a fly ball is easily catchable by an infielder, thus protecting the base runners. However, if the ball lands in foul territory, it is treated like any other foul ball.

In this scenario, the foul ball ruling means that the play is dead, and the count on the batter is unaffected. The runners do not have to return to their bases since the ball was not caught and the play is void. Consequently, they are not penalized for attempting to advance before the ball is declared foul. It's important to note that for a ball to be considered an infield fly, it must be caught in fair territory. Since it curved into foul territory, the protection of the infield fly rule does not apply.