Quiet Variation, Pin Defense

The Pin Defense is the most frequent reply to the Quiet Variation. With 4...Bg4 Black brings the light-squared bishop out before ...e6 closes it in and pins the f3 knight against the queen. Most of White's choices aim to break the pin. The engine prefers 5. h3, which forces Black to decide at once between 5...Bxf3 and the retreat 5...Bh5. After the retreat White often follows with g4 to drive the bishop away. In the database the most common move is 5. Nc3, which postpones the issue, and an early h3 frequently transposes to the lines that begin with it. 5. Be2 is the next most popular choice.

5. Qb3 removes the queen from the pin and attacks b7. After 5...Qb6 or 5...Qc7, Ne5 remains available, gaining time against the bishop. 5. cxd5 produces a structure close to the Exchange Slav, and Black typically captures on f3 so that the knight cannot later reach e5. Engines rate the position as roughly balanced, and results are close to even.