Chess Opening Theory/1. d4/1...Nf6/2. f3

2. f3!? - Paleface Attack
This move breaks the opening principle of not pushing f3 early. This move weakens white's kingside and takes away the natural development square of the g1 knight. However, this move does prepare to push e4. However, this can be stopped by playing 2...d5. If d5 is played, this move proves to be a weakening move and a waste of time.

1.d4 Nf6 2.f3!?