Classical Variation, Carlsbad Variation

The Carlsbad Variation is the modern main line of the Classical Tarrasch. By pinning the f6-knight, 9. Bg5 weakens the guard on d5 and prepares to pile up on the isolani. Black's three main answers are roughly equally common: the release 9...cxd4, which leads to the standard isolated-pawn positions; 9...c4, the Advance Variation, which gains queenside space and avoids the isolani; and 9...Be6, the Endgame Variation. The engine assessment is close to equal, and White scores slightly better in practice.