0 Lesson of the Week

In this position, I have misplayed the Benoni Defense and offered my opponent the opportunity to gain a decisive advantage. This game was played on US Chess Live in 2001. I found it looking through my databases for examples of certain common pins.

Opponent -- Stripes
USCL 13.01.2001

1.d4 Nf6 2.Nf3 c5 3.d5 e6 4.c4 exd5 5.cxd5 d6 6.Nc3 g6 7.e4 Bg7 8.Bg5 Bg4 9.Bb5+ Nbd7 10.h3 Bxf3 11.Qxf3 O-O

White to move

11.O-O

White missed the win, and after 12...Ne5 Black began to solve his self-imposed problems and went on to win.

Find the move that White should have played. As a bonus for readers of this blog, identify Black's critical error leading to the diagram position.