Chess Openings Lab
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Four Knights Game: Gunsberg Variation

The Gunsberg Variation is the Four Knights with 4.a3, a quiet move that takes b4 away from Black's bishop and knight. White wants to play d4 later without worrying about pins on c3, while Black uses the spare tempo to hit the center first.

Moves
1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.a3
ECO
C47
Engine
−0.12 · level (Stockfish 17.1, depth 20)
Played
1,633 games in our lichess sample
White scores
53.6%

Key ideas for both sides

White

  • With b4 covered, d4 comes without ...Bb4 pins. After 4...Be7 5.d4 exd4 6.Nxd4, White gets a pleasant open center.
  • In that line Nxc6 bxc6 and then 8.e5 kicks the f6-knight and gains space while Black's pawns are split.
  • Against ...g6 and ...Bg7, a plain plan with Bc4, d3, h3 and Be3 keeps things solid and rules out ...Bg4 and ...Ng4.

Black

  • Answer with 4...d5. The a3 move does nothing for White's center, so Black opens lines before White develops the kingside.
  • After 5.Bb5 Nxe4 6.Nxe5 Qg5, the queen hits g2 and the e5-knight at once. That is the sharp point of the engine line.
  • Quieter setups with ...Be7 or ...g6 and ...Bg7 are fine, but answer d4 by taking and castling quickly.
  • The a3 pawn guards b4, so the usual ...Bb4 simply loses the bishop. Find a different square for it.

Plans and pawn structure

If Black plays ...d5, the center opens and tactics on e4, e5 and g2 decide things; White's extra move a3 matters little there. In the calmer lines White aims for d4 or a slow buildup with Bc4 and d3, and the a3 pawn can later support b4 for queenside space. Black's goal is free development with ...O-O and ...d5 when possible. Without a pin on c3, Black has to find activity in the center instead.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −0.12: level. Its three top choices for Black:

  1. −0.12 4...d5 5.Bb5 Nxe4 6.Nxe5 Qg5 7.Nxc6
  2. +0.14 4...Be7 5.d4 exd4 6.Nxd4 O-O 7.Nxc6
  3. +0.15 4...g6 5.Bc4 Bg7 6.d3 d6 7.h3

Pawns, from White's side.

How it scores on lichess

1,633 rated lichess games reached this position; White scored 53.6%.

under 120055.4%
1200–159954.0%
1600–199952.3%
2000 and up52.4%

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

Where it goes next

  • Gunsberg Variation, Provincial Opening4...d6 · rare

How to play against it

Hit the center at once with 4...d5 and be ready for the forcing line with ...Qg5. If you prefer quiet play, 4...Be7 is sound, but meet d4 by taking on d4 and castling. Don't play ...Bb4 out of habit, since a3 now covers that square.

Questions

What are the moves of the Four Knights Game: Gunsberg Variation?

The Four Knights Game: Gunsberg Variation starts 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.a3. Its ECO code is C47.

Is the Four Knights Game: Gunsberg Variation good for White?

Stockfish 17.1 rates the position −0.12 at depth 20, which is level. In 1,633 lichess games from our sample, White scored 53.6%. A safe sideline for White players who want to avoid theory, but it hands Black an equal game with 4...d5.

What is the main idea of the Four Knights Game: Gunsberg Variation?

White spends a tempo to prevent pins and knight jumps to b4, planning d4 later. Black's best reply uses that tempo with 4...d5 and quick central play.

What should Black play next?

The engine's first choice is d5, with Be7 and g6 close behind. 4...d5 punishes the slow a3 by opening the center while White's kingside pieces are still at home.

Updated October 2026. Sources and method.