Please don't try narrow diamond, you should 4-5-1V attack both flank or 4-1-2-3(3 STs), he has DMC, so don't bother to use your AMC. On another hand, he has only one DC, your 3STs will outplay his lonely DC. Here are the arrow and also it's a key. If use 451V, use attack mode, yes attack (both flank), mix pass, red arrow on ST, AML/AMR, DL and DR. If you use 4-1-2-3, he can go with defensive, mix pass, play normal through the middle, red arrow on 3STs, DL and DR. Since you are 3 goals behind, why not take a risk and force counter. Good luck!