Queen's Indian Defense: Classical Variation, Tiviakov Defense

The Queen's Indian Defense: Classical Variation, Tiviakov Defense is a chess opening classified under ECO code E18 in the Indian Defences family, where Black responds to 1.d4 with 1...Nf6, including the Nimzo-Indian, Queen's Indian, and King's Indian. It is reached after 7 moves: 1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. g3 Bb7 5. Bg2 Be7 6. O-O O-O 7. Nc3 Na6. The resulting position leaves white to move.