The St. Petersburg Variation is a variation of the Nimzo-Indian Defense, catalogued as ECO E43. The line runs 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 Bxc3+ 5. bxc3 b6 6. e3 Bb7 7. Bd3 O-O 8. O-O, reaching the position shown below after 15 half-moves.
White holds the centre with pawns on d4. Development is level at three minor pieces each. It is Black to move after eight moves. Both kings have castled kingside, so play tends to shift to the centre and the opposite flank; White has doubled pawns on the c-file; White’s a-file pawn is isolated; White has the bishop pair.
On the Nimzo-Indian Defense generally: One of the most respected defenses to 1.d4. Black pins the knight and fights for central control.
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The St. Petersburg Variation goes 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 Bxc3+ 5. bxc3 b6 6. e3 Bb7 7. Bd3 O-O 8. O-O. It is a variation of the Nimzo-Indian Defense and is catalogued as ECO E43.
The St. Petersburg Variation is ECO E43. ECO codes group openings by their move order, so nearby codes cover closely related lines of the Nimzo-Indian Defense.
Stockfish evaluates the position after 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 Bxc3+ 5. bxc3 b6 6. e3 Bb7 7. Bd3 O-O 8. O-O at +0.43 at depth 18, which is a slight pull for White, within normal opening margins. Engine evaluation is only a starting point — at club level the practical value of a line is mostly about whether you know its plans better than your opponent does.
White holds the centre with pawns on d4. Development is level at three minor pieces each. It is Black to move. Both kings have castled kingside, so play tends to shift to the centre and the opposite flank; White has doubled pawns on the c-file; White’s a-file pawn is isolated; White has the bishop pair.