Panov Attack, Modern Defense, Reifir-Spielmann Line

The Reifir-Spielmann Line answers the pin 6. Bg5 with 6...Qb6, leaving d5 without the support of ...e6 and instead posting the queen on the b6–b2 diagonal, where it attacks the b2-pawn and adds to the knight's pressure on d4. White must balance pursuit of the weakened d5-pawn against defending these targets, so the play is concrete. It is the sharper relative of 6...Qa5, the Czerniak Line.