Modern Variation

The Modern Variation, 5. e3, declines to take a second pawn on a6. Instead it opens the diagonal of the f1-bishop, so that after 5...axb5 White can recapture with 6. Bxb5 and stay a pawn up with normal development. The drawback is that the d5-pawn lacks the support an early e4 would give it, and Black's most testing approach goes after it directly. In the line 6...Qa5+ 7. Nc3 Bb7 8. Bd2 Qb6 9. Nf3 Nxd5 10. a4 e6, the queen moves induce Bd2, which shuts the d-file between White's queen and d5, and Black regains the pawn.

Black need not resolve the tension at once. The most frequent reply is 5...g6, continuing with ...Bg7, ...O-O and ...Bb7 and leaving White to decide what to do about the pawns on b5 and a6. 5...axb5 is almost as common, and 5...d6 is a quieter third choice. Practical results are close to even, with White marginally ahead, and engines assess the position as a slight edge for White.