Puzzle position #3 - Week 1

Do not move any pieces until you are certain you have found the correct move. Calculate the variations in your head to practice visualization. 

This is a toughy one

only one move .-. play out the position a couple moves man 

This isn;t your everyday puzzle. If you spent some time taking in the position and calculate a couple diffrent lines you'll understand why this one move is enough

still though its satisfying to play it out