Caissa Codex
B06

Modern Defense: Semi-Averbakh Variation, Pterodactyl Variation Declined

Chess diagram: Modern Defense: Semi-Averbakh Variation, Pterodactyl Variation Declined after 5…Qa5+

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Statistics from Lichess

22 games: White 50.0% / Draw 9.1% / Black 40.9%

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Next moveGamesWhite / Draw / BlackW / D / B
1515
77

Rated Lichess games between players rated 1600 to 2500, from the Lichess opening explorer, updated Nov 1, 2026

Engine evaluation

+0.54 White is slightly better

Best play: 6. Nc3 Nc6 7. d5 Nd4 8. O-O Bg4 9. Nxd4 cxd4 10. Bxg4 dxc3

Stockfish 19, depth 30, after the line's last move. Scores are in pawns, from White's side.

Overview

Modern Defense: Semi-Averbakh Variation, Pterodactyl Variation Declined (ECO B06, Semi-Open Games) is a variation of the Modern Defense, reached after 1. e4 g6 2. d4 Bg7 3. c4 c5 4. Nf3 d6 5. Be2 Qa5+ (5 moves).

In 22 rated Lichess games between players rated 1600 to 2500, White won 50.0%, Black 40.9% and 9.1% were drawn. White's most played move here is 6. Nc3, in 68% of those games. That is too few games for the percentages to mean much.

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Other lines from the same position

Instead of 3. c4 c5 4. Nf3 d6 5. Be2 Qa5+, the position after Modern Defense also goes on to:

Cite this page

Caissa Codex. “Modern Defense: Semi-Averbakh Variation, Pterodactyl Variation Declined (B06)”. Lichess data as of 1 Nov 2026. https://chesscodex.org/openings/modern-defense-semi-averbakh-variation-pterodactyl-variation-declined

https://chesscodex.org/openings/modern-defense-semi-averbakh-variation-pterodactyl-variation-declined