Library/Openings/Sicilian Defense/Four Knights Variation ECO B45
Opening· 10 plies

Sicilian Defense: Four Knights Variation

An entry in the Encyclopedia of Chess Openings (ECO B45), reached after 10 half-moves: 1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 5. Nc3 Nf6.

Sicilian Defense: Four Knights Variation ECO B45
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Black rook
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About this opening

Sicilian Defense: Four Knights Variation is an opening in the Encyclopedia of Chess Openings, classified under code B45. ECO group B (B00–B99) covers semi-open games (1.e4 with Black playing anything other than 1…e5), with the Sicilian, French, Caro-Kann and Pirc/Modern at its heart. This particular variation is reached after 10 half-moves from the starting position, with the move sequence 1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nc6 5. Nc3 Nf6.

It belongs to the Sicilian Defense family. Within that family this is a sub-variation (the Four Knights Variation line).

The opening sequence in prose form: 1.e4 c5, 2.Nf3 e6, 3.d4 cxd4, 4.Nxd4 Nc6, 5.Nc3 Nf6. From this position 2 named continuations are recorded in the encyclopaedia, each leading to a distinct theoretical line.

Use the interactive board above to walk through the moves position-by-position. Click any move in the navigation to step backwards, or use the keyboard arrow keys. The list of recorded continuations sits directly below the board. For statistical data — how often master-level players have reached this position, White's win-rate, draw frequency, Black's score — see the panel in the right column.

Caissly's coverage of B45 extends through every named sub-variation in this line and across all four locales (English, Spanish, Portuguese, Russian). Where editorial commentary exists for a specific variation it appears as the page body; otherwise the page presents the structural data, board, and statistics as shown here.