Chess Opening Theory/1. e4/1...e5/2. Qh5/2...Nc6/3. Bc4/3...g6/4. Qf3/4...Nf6/5. Nc3

= Parham Attack =

5. Nc3
Moving the knight to c3 seems natural, since it develops the knight and prevents Black's d-pawn advance. However, this move can be considered a mistake. This is because Black can gain a tempo by playing Nd4!, moving to an outpost which threatens to win the queen while also threatening to fork white’s pieces at the same time.