The ...Nd7 Trap

The ...Nd7 Trap arises after

1.e4 g6 2.d4 Bg7 3.Nf3 d6 4.Bc4

when 4...Nd7 looks like a perfectly normal developing move. However 4...Nd7 blocks the bishop's protection of e6 and much worse; it smothers the queen.

Here are six examples.

       Arnason vs Pribyl  1990

       Santasiere vs Byrne  1946

       Srebrnic vs Motoc 2007

       Djordjevic vs Trickovic  2012

       Maia vs Pereira Vilalba  2001

       Hughey vs Day  2001

Interesting

I was a victim of this trap.

The same combination of a knight on f3 and a bishop on c4 can wreak havoc even when Nc6 is played and the queen is not smothered, as in our vote chess game "Serra"

http://www.chess.com/groups/forumview/vc---serra---engine-analysis

The best thing to do when the bishop comes to c4 is to blunt it with e6.

I mostly try h6 or e6 when I see that bishop and knight hanging back there.
h6 solves the problem that attacking your fianchetto'd position becomes a lot harder. g5 is a weak square for black a lot of time. 

I played into this trap against a roughly equal rated opponent and thankfully they did not see the strength of Bxf7+. A free lesson after my comp (and the player beside my board) scolded me after the game.

e6 is now what I play almost reflexively

...Bg4 of course will fall into that same trap

I play c6

Oops... I was also a victim of this trap... :(

So to avoid the trap would ........

But Black is still in deep trouble; King stuck in the middle unable to castle and White has plenty of attacking potential. Better to play ...e6 and avoid all that.