Modern Defense

The Modern Defense is the main line of the Steinitz Variation of the Scotch Game. After 4...Qh4 5. Nc3, which defends e4, Black adds 5...Bb4 and pins the knight. The defender of the e-pawn is now tied down, so Black threatens to take on e4 with the queen. The established reply is 6. Be2, a pawn sacrifice. After 6...Qxe4 7. Nb5, White targets c7 and the uncastled king. Play goes either 7...Bxc3+ 8. bxc3 Kd8 9. O-O Nf6 or 7...Kd8 8. O-O Bxc3 9. Nxc3 Qd4. Black keeps the extra pawn in both lines but loses the right to castle and falls behind in development. The other capture order, 6...Bxc3 7. bxc3 Qxe4, runs into 8. Nb5.

The engine rates the position as clearly better for White and prefers 6. Be2, 6. Be3 and 6. Qd3. In online games 6. Nxc6 is the most common choice and 6. Qd3 the next, but Black scores slightly better than White after both. White does much better after 6. Be2.