Chess Openings Lab
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Slav Defense: Two Knights Attack

The Two Knights Attack of the Slav is 4.Nc3 dxc4, where Black takes on c4 before White has played e3 or a4. White chooses between a4, e3 and e4 to recover the pawn or build a center, while Black aims to keep it or develop with ...Bf5.

Moves
1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4
ECO
D15
Engine
+0.38 · a slight edge for White (Stockfish 17.1, depth 20)
Played
185 games in our lichess sample
White scores
60.3%

Key ideas for both sides

White

  • 5.a4 stops ...b5 for good and leads to the Czech Variation after 5...Bf5.
  • Ne5 hits the c4 pawn at once and prepares f3 and e4 for a big center.
  • 5.e4 is the Geller Gambit, building a center and letting Black keep c4 for now.
  • 5.g3 with Bg2 is a quieter fianchetto line where Ne5 wins back c4.

Black

  • ...Bf5 develops the c8 bishop before ...e6 locks it in, and it eyes the e4 square.
  • ...b5 holds c4 if White does not stop it with a4, gaining queenside space.
  • ...e6 and ...Bb4 pin the c3 knight and slow down White's e4 push.
  • ...Nbd7 prepares ...e5 to strike the center and free Black's game once the king is safe.

Plans and pawn structure

White must decide how to recover c4. With a4, the game becomes the Czech Variation and White plays Ne5 or e3. With e4, it becomes the Geller Gambit, and Black holds the pawn with ...b5. With e3, Black also gets ...b5 in. Black aims for ...Bf5, ...e6, ...Bb4 and ...Nbd7, then breaks with ...e5 or ...c5 once the king is safe and the pieces are developed.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position +0.38: a slight edge for White. Its three top choices for White:

  1. +0.38 5.a4 Bf5 6.Ne5 Nbd7 7.Nxc4 Nd5
  2. +0.14 5.g3 a5 6.Ne5 g6 7.Nxc4 Bg7
  3. +0.04 5.e4 b5 6.Be2 e6 7.O-O Bb7

Pawns, from White's side.

How it scores on lichess

185 rated lichess games reached this position; White scored 60.3%.

1600–199967.8%
2000 and up56.3%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

Where it goes next

How to play against it

As White, play 5.a4 to stop ...b5, then win c4 back with Ne5 or e3 and Bxc4. Avoid letting Black keep the pawn with ...b5 and ...Bb7. Aim for e4 only once your pieces support it, and watch out for ...Bb4 pins on the c3 knight.

Questions

What are the moves of the Slav Defense: Two Knights Attack?

The Slav Defense: Two Knights Attack starts 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4. Its ECO code is D15.

Is the Slav Defense: Two Knights Attack good for Black?

Stockfish 17.1 rates the position +0.38 at depth 20, which is a slight edge for White. Main-line theory for both sides; club players should know which fifth move they prefer and its plans.

What is the main idea of the Slav Defense: Two Knights Attack?

Black takes on c4 and White decides how to recover it. The main choices are a4 for the Czech Variation, e3 for the Alekhine line and e4 for the Geller Gambit.

What should White play next?

The engine's first choice is a4, with g3 and e4 close behind. 5.a4 stops ...b5 and prepares to recover the c4 pawn with Ne5 or e3.

Updated October 2026. Sources and method.