Chess Opening Theory/1. f4/1...e5/2. fxe5/2...d6/3. exd6/3...Bxd6/4. Nf3/4...g5/5. h3

5.h3??
This unfortunate move caused the loss of three white players in Lakdawala's database. While white has stopped g4, the price is far too high, he just allowed Bg3 mate!