I am a mid-feilder and my coach usually ask me to defend zonal only.When player come to my zone I follow him and try to take ball possesion.If player go out of my zone then I try to go back slowly and wait for my defenders to snatch ball from them pass me.Sometime if opppnent come to our pitch with more attakers(mostly when they are losing) then I preffer to go back and suppprt defense and strikers also join us if I call them as I am captain lol