Tarrasch Defense

The Tarrasch Defense of the Catalan, 4...c5 5. Nf3 Nc6, carries the active approach of the Queen's Gambit Tarrasch into the Catalan move order. Black does not simply hold d5 behind a closed chain. The c-pawn strikes at d4 and the knight adds pressure, so Black develops freely and gets central tension in return for possible pawn weaknesses. The structure often turns on the d5-pawn. When the c- and d-pawns are exchanged, Black can be left with an isolated or hanging center. The fianchettoed bishop on g2 then bears straight down on d5, which is why this setup is regarded as a demanding test of Tarrasch-style play.

White's most common choice is 6. O-O, completing development and keeping the tension. The second most popular is 6. cxd5, which clarifies the center immediately and fixes Black's pawn structure. The less common 6. Nc3 adds another attacker to d5. The engine gives White a slight edge, and White scores somewhat better in practice. The line is a less frequent alternative to the Open and Closed Catalan.