How far up field can a soccer defender go?

Answer 1

A defender in soccer moves up when the ball is close to the oposite net. If a striker from the other team stays back, one defender should stay to cover him. You could also try to make him offside by stepping up, but not past the halfway line.

Answer 2

Any player may play anywhere on the field. Note that the goalkeeper loses some privileges once they leave their own penalty area.