Prins Variation

The Prins Variation answers the attack on e4 with 5. f3 rather than the usual 5. Nc3. Because the knight stays at home, the c-pawn is still free to advance, and White keeps the option of c4 and a Maroczy Bind formation. The cost is a slightly weakened kingside and a pawn move instead of development. Black can sidestep the line entirely with the move order 3...Nf6. In practice 5...a6 is the most frequent reply, ahead of 5...g6 and 5...e5, and the engine considers the position level.

The principled answer is 5...e5, which drives the knight away before White can play c4 comfortably. After 6. Nb3 Black can target the c4 square with 6...Be6 7. c4 Nbd7 8. Be3 Rc8 9. Nc3 Bxc4, or prepare an early central break with 6...d5 7. Bg5 d4, gaining space before White clamps down. The Venice Attack, 6. Bb5+, interposes a check so the knight can go to f5, but it abandons the c4 plan because Black gains time with ...a6 and ...b5. Play then runs 6...Nbd7 7. Nf5 d5 8. exd5 a6 9. Ba4 b5 10. Bb3 Nb6, with equal chances.