Chess Openings Lab
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Four Knights Game: Glek System

The Glek System is the Four Knights with 4.g3, preparing Bg2 instead of sending the f1-bishop to b5 or c4. White wants a quiet setup with d3, O-O and later Nh4 and f4, while Black uses the slow move to grab active squares for the bishops.

Moves
1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.g3
ECO
C47
Engine
−0.28 · level (Stockfish 17.1, depth 20)
Played
676 games in our lichess sample
White scores
53.0%

Key ideas for both sides

White

  • Finish the setup with Bg2, d3 and O-O. The g2-bishop backs up e4 and looks down the long diagonal toward b7.
  • Nh4 followed by f4 is the main kingside idea, hitting e5 and opening the f-file for the rook once White has castled.
  • Na4 can chase or trade a bishop on c5, as in the top engine line with 8.Na4. Keep that option ready whenever Black plays ...Bc5.

Black

  • 4...Bc5 is the engine's choice. The bishop hits f2 and stays active because the fianchetto never contests the a7-g1 diagonal.
  • Add ...d6 and ...a5. The a-pawn stops b4 and frees a7 as a retreat, so Na4 does not win the bishop pair cheaply.
  • 4...d5 opens the center before White castles. After 5.exd5 Nxd5 6.Bg2 Bc5, Black castles quickly, though White can trade with Nxd5.
  • ...Nd4 is a handy resource later, trading off White's f3-knight before Nh4 and f4 can start.

Plans and pawn structure

The pawns on e4 and e5 tend to stay put, so the play moves to the wings. White's standard plan is Nh4, f4 and a kingside push, with the g2-bishop sheltering the king. Black can meet it with ...Nd4 to trade the f3-knight before it jumps to h4, or with ...a5-a4 for queenside space. If Black opens the game early with ...d5, quick development matters more than White's fianchetto.

Where the engine's main line heads: Open game: e4 against e5. An open game: e4 against e5. Development, the f7 and f2 squares, and the d4 or d5 break are what count.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position −0.28: level. Its three top choices for Black:

  1. −0.28 4...Bc5 5.Bg2 d6 6.d3 a5 7.O-O
  2. +0.12 4...d5 5.exd5 Nxd5 6.Bg2 Bc5 7.O-O
  3. +0.16 4...Bb4 5.Bg2 O-O 6.O-O Bxc3 7.dxc3

Pawns, from White's side.

How it scores on lichess

676 rated lichess games reached this position; White scored 53.0%.

under 120046.5%
1200–159952.0%
1600–199957.3%
2000 and up61.9%

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

How to play against it

Develop actively instead of copying White. 4...Bc5 or 4...d5 both use the fact that g3 is slow. 4...Bb4 is fine too, but giving up the bishop with ...Bxc3 lets White recapture dxc3 and open lines for the c1-bishop. Keep the dark-squared bishop unless the trade wins something concrete.

Other lines with this name

The lichess opening list also files this line under the same name, though it reaches a different position: 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.g3 d5 5.exd5 Nxd5 6.Bg2 Nxc3 7.bxc3.

Questions

What are the moves of the Four Knights Game: Glek System?

The Four Knights Game: Glek System starts 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.g3. Its ECO code is C47.

Is the Four Knights Game: Glek System good for White?

Stockfish 17.1 rates the position −0.28 at depth 20, which is level. In 676 lichess games from our sample, White scored 53.0%. Suits White players who like slow maneuvering and a later kingside pawn push; it gives Black an easy game if White drifts.

What is the main idea of the Four Knights Game: Glek System?

White picks a quiet fianchetto, keeps e4 solid and plans Nh4 and f4 later. Black gets free development and should use it with ...Bc5 or an early ...d5.

What should Black play next?

The engine's first choice is Bc5, with d5 and Bb4 close behind. 4...Bc5 puts the bishop on its best diagonal, aimed at f2, since the fianchetto never challenges it.

Updated October 2026. Sources and method.