Nimzo-Indian Defense: Three Knights Variation, Korchnoi Variation

1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Nf3 c5 5.d5

ECO E21

The Nimzo-Indian Defense: Three Knights Variation, Korchnoi Variation is a chess opening line in the Nimzo-Indian Defense complex, reached after 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Nf3 c5 5.d5.

It is catalogued under code E21 in the Encyclopaedia of Chess Openings (ECO).

The defining move d5 is chosen by White on move 5.

Study this line with a grandmaster

This position is covered in the Nimzo-Indian Defense course: a GM-authored repertoire you study move by move, then practice against a human-like AI opponent.

Every chess term used here is defined in the chess terms glossary. Browse all opening courses or the full ECO code index.