Petrov's Defense: Cozio Attack: what should White play?

In the symmetrical setup of the Petrov's Defense: Cozio Attack, White's most precise move according to engine evaluation is the immediate queen trade Qxe7+, which holds an engine evaluation of +0.09. This move resolves the central tension on the e-file and leads directly into a balanced endgame where White develops minor pieces smoothly. Chosen in 49.9% of games (726K recorded), it provides a stable structure while depriving Black of any dynamic queen counterplay.

Central Simplification with Qxe7+

Opting for Qxe7+ immediately transitions the game into a queenless middlegame. Although White scores 45.2% from this position, it remains the engine's top choice because it neutralizes active queen options on the open file. An illustrative engine continuation follows Qxe7+ Bxe7 g3 c5 Bg2 Nc6, where White fianchettoes the light-squared bishop toward g2 to target the long diagonal.

Minor Piece Development Alternatives

White frequently bypasses the immediate queen capture in favor of development, relying on Black to initiate the trade on e2. The most popular developing choice is Bg5, played in 33.3% of games (484K recorded) with an evaluation of +0.01, scoring 51.7% for White. In the illustrative line Bg5 Qxe2+ Bxe2 Be7 Nc3 h6, Black exchanges queens anyway, allowing White to recapture with the bishop and gain rapid piece mobilization.

Flexible Developing Options

Another robust developmental option is Nc3, occurring in 16.4% of games (238K recorded) with an evaluation of +0.08 and White scoring 51.0%. The engine illustrates this branch with Nc3 Nc6 Bg5 Qxe2+ Bxe2 Be7. Less common choices include the quiet pawn move h3 (eval +0.03, 3.7K recorded) and Bd2 (eval +0.02, 1.7K recorded), both of which retain a practically equal position.