Black's Knight removes White's king's pawn on
K4(e4) and threatens 5..KtxBP to fork White's Q+R. White develops his Queen's Knight to
QB3(c3) to attack Black's knight, dismissing Black's threat.
White Black
1. P-K4 P-K4
2. Kt-KB3 Kt-KB3
3. KtxP P-Q3
4. Kt-B4 KtxP
5. Kt-B3