Classical Defense, Boden Variation

The Boden Variation of the Classical Defense arises after 3...Bc5 4. c3 Qe7, with the queen guarding e5 ahead of time. It answers the threat created by 4. c3. By controlling d4, that move takes away Black's usual tactical defense of the pawn after Bxc6 and Nxe5. White most often castles with 5. O-O, while 5. d4 challenges the center and the bishop at once. The line is uncommon, and engines give White a clear advantage.