Grünfeld Variation

The Grünfeld Variation of the Bogo-Indian Defense, 1. d4 Nf6 2. c4 e6 3. Nf3 Bb4+ 4. Nbd2, is the less common of White's two independent replies to the check, behind 4. Bd2. Blocking with the queen's knight keeps the c3-square free for a pawn, so a3 can follow and put the question to the bishop. Black must then either give up the bishop for the knight, handing White the two bishops, or retreat and lose time. The price is that the knight stands less actively on d2 than on c3 and shuts in the c1-bishop for the moment.

Black's most popular answer is 4...O-O, keeping the bishop in place until White commits. 4...b6 heads for a Queen's Indian-style fianchetto, and 4...d5 builds a Queen's Gambit Declined-type center where the d2-knight exerts little pressure. The engine also rates the immediate retreat 4...Be7, which avoids conceding the bishop pair. The play is positional, without much forcing theory. The engine assesses the position as a slight edge for White, and White scores somewhat better than Black in online games.