Sicilian Defense: Four Knights Variation

Strategic Summary & Main Idea

The Sicilian Four Knights develops both Black knights before any pawn: after 4...Nf6 5.Nc3 Nc6, Black prepares ...Bb4, pinning the knight that defends e4, and ...d5, the break that equalises Sicilians. The position measures +0.48, within the normal range of White's edge in an open Sicilian. What the entry shows is which White moves keep that number. The exchange 6.Nxc6 followed by 7.e5 keeps it (+0.49); the main line with 6.Ndb5 drops to +0.37; and the check 7.Nd6+, which looks like winning the c8 bishop, gives the whole edge away and measures −0.08.

The pawn structure this opening produces

The Four Knights starts with the open Sicilian structure — a White pawn on e4, Black pawns on e6 and d7 — and with both Black knights already developed. That order defines the game: with the knight on f6 attacking e4 and the f8 bishop free to go to b4, Black threatens to exchange e4's defender and play ...d5 with an open centre. So White has three paths. In the 6.Ndb5 line, the knight threatens d6 and forces ...Bb4; after a3 and the exchange on c3, White keeps the bishop pair and the structure opens with ...d5 and exd5, leaving Black an isolated pawn on d5 or a full central exchange. In the 6.Nxc6 bxc6 exchange, Black gains a c6 pawn supporting d5, and White answers 7.e5, driving the knight away and gaining space — the structure becomes a French with Black's b-pawn already on c6. With 6.Be2 or 6.Bd3, White gives up gaining time and accepts a symmetrical position. The d6 square is the weak point of Black's structure in every version, and a knight on d6 is exactly what Black cannot allow without getting something back.

Main Variations of the Sicilian Defense: Four Knights Variation

Evaluations measured by us with Stockfish 19, depth 22, on 15/09/2026.

Frequently asked questions

What is White's best answer to the Sicilian Four Knights?

By the measurement, 6.Nxc6 bxc6 7.e5, which keeps +0.49 after 7...Nd5 8.Ne4 Qc7 9.f4 Qb6 10.c4 Bb4+ 11.Ke2. The main line with 6.Ndb5 Bb4 7.a3 measures slightly less, +0.37. Both are the serious tests; quiet development with 6.Be2 or 7.Bd3 leads to equality.

Why does the 7.Nd6+ check not work?

Because the knight on d6 has no support and trades for the c8 bishop. After 6.Ndb5 Bb4 7.Nd6+ Ke7 8.Nxc8+ Rxc8, Black has lost castling but exchanged the most passive piece it had, and the position measures −0.08. The move that keeps the pressure is 7.a3, at +0.37.

Is the Sicilian Four Knights a good choice for Black?

It is solid: +0.48 after 5...Nc6, in the range of the open Sicilians. It needs less theory than the Najdorf or the Sveshnikov, because the ideas repeat — ...Bb4, ...d5 and the d6 square — but Black must know the answer to 7.e5, where centralising the knight is worth almost half a pawn more than retreating it.

Guides on this opening

• The Four Knights Sicilian: the main line, the check that fails and the test the engine prefers

Common Mistakes & Where Most Amateurs Go Wrong

• 01 Giving the 7.Nd6+? check after 6.Ndb5 Bb4. The knight looks dominant, but after 7...Ke7 8.Nxc8+ Rxc8 it trades for the c8 bishop, Black's worst piece, and White loses time and the edge: −0.08, against +0.37 for 7.a3. The line: 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 Nc6 6.Ndb5 Bb4 7.Nd6+ Ke7 8.Nxc8+ Rxc8 −0.08
• 02 Retreating the knight to g8 against 6.Nxc6 bxc6 7.e5. The piece goes home and White develops with time and space: +0.96, against +0.49 for the centralising 7...Nd5. The line: 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 Nc6 6.Nxc6 bxc6 7.e5 Ng8 +0.96