d4 v. the Marshall defense

Just learn how to jump on the Marshall defense early, so that you can take advantage of black failing to play 2. .. e6, 2. .. c6 or 2. dxc4.. 

What you'll see in these games is players who will play this ... stuff.. and if you let them get comfortable, maybe they can play a decent chess.  But press your advantage and put them in waters that are a little hard to navigate, and suddenly you're in a well defended position with plenty of play.