Exchange Variation, Bogoljubow Variation

After 4. Nc3 Nf6 5. Bg5, Black meets the pin with 5...Nc6, keeping the position symmetrical rather than breaking with ...c5 or unpinning at once with ...Be7. The knight supports d5 and eyes b4 and e5, and Black is ready to copy whatever setup White adopts. 6. Nf3 is the most common reply, followed by 6. Bb5, which pins the c6-knight in turn, and 6. Bxf6, which gives up the bishop pair to damage Black's kingside structure. The engine judges the position roughly balanced, and on Lichess the decisive results split evenly.