Petrov's Defence is a chess opening characterised by the following moves:

:1. e4 e5

:2. Nf3 Nf6

Although this response has a long history, it was first popularised by Alexander Petrov, a Russian chess player in the mid-19th century. In recognition of the early investigations by the Russian masters Petrov and Carl Jaenisch, this opening is also called the Russian Game (or Russian Defence), which is the predominant name in some countries. The Petrov has been adopted by many of the world's leading players, including world champions Vasily Smyslov, Tigran Petrosian, Anatoly Karpov, and Vladimir Kramnik, along with grandmaster Fabiano Caruana and others.

The Petrov has a drawish reputation; though there are attacking opportunities for both sides, and a few lines are quite . Often a trade occurs and Black, after gaining a tempo, has a well-placed knight. Pillsbury's game in 1895 against Emanuel Lasker testifies to this. The Black counterattack in the also avoids the Ruy Lopez, Italian Game, and Scotch Game. White's most common response is 3.Nxe5, but 3.d4 and 3.Nc3 (most often leading to the Four Knights Game) are also common, and 3.Bc4 and 3.d3 are occasionally seen.

The Encyclopaedia of Chess Openings codes for Petrov's Defence are C43 (for 3.d4) and C42 (for all other lines).

Variations

White's two main choices are 3.Nxe5 and 3.d4. 3.Nxe5 is more popular but they often lead to similar positions and "there is no clear reason to prefer one move over the other".

3.Nc3 may transpose to the Four Knights Game. 3.Bc4 may lead to the Boden–Kieseritzky Gambit or transpose to the Two Knights Defence or Bishop's Opening. Occasionally seen is the 3.d3.

Examined in this article are the following common variations:

  • 3.Nxe5 (Classical Variation)
  • 3...d6
  • 4.Nf3 Nxe4
  • 5.d4 d5 6.Bd3 (main line)
  • 6...Nc6 7.0-0 Be7
  • 8.c4 (Jaenisch Variation)
  • 8.Re1
  • 6...Bd6 7.0-0 0-0
  • 8.c4 c6 (Staunton Variation)
  • 8.c4 Bg4 (Marshall Variation)
  • 6...Be7 7.0-0 0-0
  • 6...Nc6 7.0-0 Bg4
  • 6...Bf5
  • 5.Nc3 (Nimzowitsch Attack)
  • 5.Qe2 (Lasker Variation)
  • 5.d3
  • 5.c4 (Kaufmann Attack)
  • 5.Bd3 (Millennium Attack)
  • 4.Nc4 (Paulsen Attack)
  • 4.Nd3 (Karklins-Martinovsky Variation)
  • 4.Nxf7 (Cochrane Gambit)
  • 3...Nxe4 (Damiano Variation)
  • 3...Nc6 (Stafford Gambit)
  • 3.d4 (Steinitz Variation)
  • 3...Nxe4
  • 4.Bd3
  • 4...d5 5.Nxe5 Nd7
  • 4...d5 5.Nxe5 Bd6
  • 4...Nc6 (Murey Variation)
  • 4.dxe5
  • 4.Nxe5 d5 5.Bd3 (4.Bd3 main line, by transposition)
  • 4.Nxe5 d6 5.Nf3 (3.Nxe5 main line, by transposition)
  • 3...exd4
  • 4.e5 Ne4 5.Qxd4 d5 6. exd6 Nxd6 (main line)
  • 4.Bc4 (Urusov Gambit)
  • 3...d5
  • 3...d6 (Philidor Defence, by transposition)
  • 3.Bc4 (Italian Variation)
  • 3...Nxe4 4.Nc3 (Boden–Kieseritzky Gambit)
  • 3.Nc3 (Three Knights Game)
  • 3...Nc6 (Four Knights Game, by transposition)
  • 3...Bb4
  • 3.d3 (Closed Variation)

<span class="anchor" id="Classical Variation"></span> Classical Variation: 3.Nxe5

After 3.Nxe5, the standard reply for Black is 3...d6 (3...Nxe4?! is usually considered an error). After 4.Nf3 Nxe4, White's main options are 5.d4, intending to undermine the knight on e4, and 5.Nc3, aiming for rapid development with queenside castling and a kingside attack. Other moves offer little hope for an advantage.

<span class="anchor" id="Main line"></span> Main line: 3...d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3

This is the most common line, reaching a position that has occurred in thousands of top-level games. The position is similar to an Exchange French in which Black has played the extra move ...Nf6–e4, though this extra move is not necessarily to Black's advantage. White will try to drive Black's advanced knight from e4 with moves like c4 and Re1. In practice White is usually able to achieve this, but at some structural cost such as having to play c4, which balances out.

A variety of sixth moves are possible for Black: 6...Bd6, 6...Be7, and 6...Nc6 are the most common. 6...Be7 and 6...Nc6 often transpose to the same line via 6...Be7 7.0-0 Nc6 or 6...Nc6 7.0-0 Be7. The most common move for White is then 8.c4.

<span class="anchor" id="Jaenisch Variation"></span> Jaenisch Variation: 6...Be7 7.0-0 Nc6 8.c4

This line has been credited to Carl Jaenisch and has been popular for over a century. Black's most common reply to 8.c4 is 8...Nb4. After this, White usually retreats the bishop with 9.Be2, a line popularised by Anatoly Karpov.

  • The oldest reply, 8...Be6. It is considered playable but weak to 9.cxd5 Bxd5 10.Nc3 or 9.Re1 Nf6 10.c5.

8.Re1

8.Re1 is a serious (but less frequent) alternative to 8.c4.

White's fifth move alternatives

  • 5.Qe2, the Lasker Variation, forces simplification and a likely draw after 5...Qe7 6.d3 Nf6.
  • 5.d3 is a quieter line. Play may transpose into an Exchange French after 5...Nf6 6.d4 d5.
  • 5.c4, the Kaufmann Attack, was also explored by Keres. The idea is to discourage ...d5 before undermining the Black knight on e4, however this plan is rather slow, and Black can instead choose to retreat the knight to g5, e.g. 5...Be7 6.d4 0-0 7.Bd3 Ng5 with equality. Alternatively, Black can counter White's plan with 5...Nc6, intending to answer 6.d4 with 6...d5!
  • 5.Bd3 is the Millennium Attack.

White's fourth move alternatives

  • 4.Nxf7 (Cochrane Gambit). This line was labelled "speculative but entertaining" by Nick de Firmian in Modern Chess Openings. He evaluates the position in Topalov–Kramnik, Linares 1999 as offering chances for both sides after 4...Kxf7 5.Nc3 c5 6.Bc4+ Be6 7.Bxe6+ Kxe6 8.d4 Kf7 9.dxc5 Nc6. but it was played in the World Chess Championship 2018 between Magnus Carlsen and Fabiano Caruana.

Black's third move alternatives

<span class="anchor" id="Damiano Variation"></span> Damiano Variation: 3...Nxe4

The Damiano Variation, 3...Nxe4, has traditionally been regarded as an error, though it has occasionally been seen in recent grandmaster play. Black must play accurately to avoid an immediately losing position. After 4.Qe2 there are several moves that Black must avoid.

  • 4...Nf6 5.Nc6+ wins the queen.
  • 4...d5 5.d3 Qe7 6.dxe4 Qxe5 7.exd5 and Black loses a pawn.
  • 4...d6? 5.Nxf7 Kxf7 6.Qxe4 and Black has lost a pawn and the ability to castle.

Best is 4...Qe7 5.Qxe4 d6 6.d4 dxe5 7.dxe5 Nc6, and after 8.Nc3 Qxe5 9.Qxe5+ Nxe5 10.Nb5 (or 10.Bf4) White has a moderate advantage.

<span class="anchor" id="Stafford Gambit"></span> Stafford Gambit: 3...Nc6?!

Recently dubbed the Stafford Gambit, 3... Nc6 is considered dubious, but it sets a number of traps. It was advocated by Eric Rosen in the early 2020s and became popular in online games. After 4.Nxc6 dxc6, White wins a pawn but must play carefully. After 5.e5 (5.d3 is better) Ne4 6.d3?? (White should play 6.Nc3, 6.d4, or 6.Qe2) 6...Bc5! and White resigned in Lowens–Stafford, US correspondence game 1950. Following 5.d3 Bc5, White must avoid the Légal Trap 6.Bg5?? Nxe4!, and if 7.Bxd8 (relatively best but still losing is 7.Be3) 7...Bxf2+ 8. Ke2 Bg4. Instead, White should play 6.Be2 h5 7.h3 (7.c3 with 8.d4 to follow is also good) and after 7...Qd6 8.c3 Black has insufficient compensation for the pawn, though White must still play carefully.

Other lines

  • 3...Qe7 is inferior, as 4.d4 d6 5.Nf3 Qxe4+ 6.Be2 gives White a large lead in development.

<span class="anchor" id="Steinitz Variation"></span> Steinitz Variation: 3.d4

3.d4 was the preferred move of World Champion Wilhelm Steinitz, who recommended it in his The Modern Chess Instructor (1889) and played it three times against Harry Nelson Pillsbury in the Saint Petersburg 1895–96 tournament, winning two games and drawing one. It has become more popular in the 21st century, though still behind 3.Nxe5.

Black's most common reply is 3...Nxe4. After White's usual 4.Bd3, the main line continues 4...d5 5.Nxe5, followed 5...Nd7, a modern move that has become predominant, or the older symmetrical 5...Bd6.

The asymmetrical lines 4.dxe5 and 5.dxe5 are also not uncommon, particularly when White is determined to avoid a draw. 4.Nxe5 is also possible but uncommon as it gives Black the option to transpose to the Classical Variation with 4...d6. Otherwise, it usually reaches the 3.d4 Nxe4 4.Bd3 main line after 4...d5 5.Bd3.

Main line: 3...Nxe4 4.Bd3 d5 5.Nxe5 Nd7

After 3...Nxe4 4.Bd3 d5 5.Nxe5, Black's best regarded move is 5...Nd7, which has been advocated by Vladimir Kramnik, Viswanathan Anand, and others. White typically plays 6.Nxd7, 6.Nc3, or 6.0-0 in response. This line was considered problematic for Black until 1980, when Danish GM Bent Larsen played a pawn sacrifice in a game against World Champion Anatoly Karpov and won as Black. This brought great attention to 5...Nd7, which had not been Black's main reply at the time, as White was considered to have easy development after the sharp 6.Qe2.

<span class="anchor" id="Murey Variation"></span> Murey Variation: 4...Nc6

An alternative for Black to the main line with 4.Bd3 d5 is 4.Bd3 Nc6, the Murey Variation. Though Black's knight on e4 appears to hang, 5.Bxe4 can be met with 5...d5!, where White's bishop has no good retreat squares; if 6.Bd3, 6...e4! forks White's knight and bishop. Instead, more typical for White are 5.Nxe5 and 5.dxe5; 5.d5 and 5.0-0 are also seen.

4.dxe5

This is a sharper line that induces an asymmetrical pawn structure comparatively early. It can continue 4...d5 or 4...Bc5. After 4...d5, 5.Nbd2 is the main move for White; Black's most common responses are 5...Nxd2, 5...Nc5, and 5...Qd7. After 4...Bc5, play tends to continue either 5.Bc4 Nxf2 or 5.Qd5 Bxf2, which has been played by Pentala Harikrishna.

Black's third move alternatives

3...exd4

After 3...exd4, the usual continuation is 4.e5 Ne4 (4...Qe7?! 5.Be2 is better for White) 5.Qxd4 (5.Qe2 is also possible) d5 6.exd6 Nxd6, followed by 7.Nc3 Nc6 8.Qf4 or 7.Bd3 Nc6 8.Qf4. 4.Bc4 instead transposes into the Urusov Gambit, which is not considered wholly sound.

3...d5

3...d5 often ends up transposing to one of the earlier lines. The most important independent line begins with 4.exd5; a typical continuation is 4...exd4 5.Bb5+ c6 6.dxc6, followed by 6...bxc6 or 6...Qa5+.

Other lines

  • 3...d6 transposes to Philidor's Defence.

<span class="anchor" id="Italian Variation"></span> Italian Variation: 3.Bc4

3.Bc4 is an occasionally seen alternative for White, often with the intention of playing 3...Nxe4 4.Nc3, the Boden–Kieseritzky Gambit. Black's main alternatives to 3...Nxe4 are 3...Nc6, transposing to the Two Knights Defence, and the aggressive 3...d5.

<span class="anchor" id="Boden–Kieseritzky Gambit"></span> Boden–Kieseritzky Gambit: 3...Nxe4 4.Nc3

The gambit is not considered wholly sound, since Black has several viable options. Black can accept the gambit with 4...Nxc3 5.dxc3 f6, but must play carefully after 6.0-0 (for example 6...Bc5?? 7.Nxe5! is disastrous; 6...d6 and 6...Nc6 are good).

Another more aggressive try is 6.Nh4, where White goes for a quick assault on Black's king, but Black can maintain a small advantage if he plays cautiously via 6...g6 7.f4 Qe7 8.f5 Qg7 9.Qg4 Kd8. Another possibility is returning the gambit pawn with 4...Nxc3 5.dxc3 c6 6.Nxe5 d5, which equalises.

A third possibility is transposing to the Italian Four Knights Game with 4...Nc6, and if 5.Nxe4, 5...d5. If 5.Bxf7+?, then 5...Kxf7 6.Nxe4 d5 gives Black the and control of the . If 5.0-0, Black plays 5...Nxc3 6.dxc3 and now Black can play 6...Qe7!, after which Bobby Fischer wrote that "White has no compensation for the Pawn", or 6...f6 transposing to the main line of the Boden–Kieseritzky. Black also has lines beginning 6...Be7 and 6...h6.

Other lines

  • 3.Bc4 Nxe4 4.d3 is an alternative to the Boden–Kieseritzky Gambit for White. Possible lines include 4...Nf6 5.Nxe5 d5 6.Bb3 Bd6 7.d4 0-0 8.0-0 c5, and 4...Nc5 5.Nxe5 d5 6.Bb3 Nxb3 (or 6...Bd6).
  • 3.Bc4 Nxe4 4.Nxe5 typically leads to positions similar to the main line Petrov but with White down a tempo after 4...d5 5.Be2 (or other retreats).

<span class="anchor" id="Three Knights Game"></span> Three Knights Game: 3.Nc3

This leads to the Three Knights Game of Petrov's Defence. It is often played by White in order to avoid lines unique to the Petrov, as 3...Nc6, which transposes to the Four Knights Game, is Black's most common and best-regarded response. It can also be reached via 2.Nc3 Nf6 (the Vienna Game) 3.Nf3. The main alternative is 3...Bb4, and after 4.Nxe5 0-0 5.Be2 Re8 6.Nd3 Bxc3 7.dxc3 Nxe4 8.Nf4 d6 9.0-0 White has a slight advantage due to the bishop pair.

<span class="anchor" id="Closed Variation"></span> Closed Variation: 3.d3

White declines to exchange any pieces and instead defends the pawn on e4. Black usually responds with 3...Nc6. White often intends either 4.Be2 or to fianchetto with 4.g3 and 5.Bg2. These lines are also sometimes reached by transposition, and are also the main lines of two rare third moves for White after 2.Nf3 Nc6, 3.g3 (the Konstantinopolsky Opening) and 3.Be2 (the Tayler Opening), which both most often continue 3...Nf6 4.d3.

The symmetrical 3...d6 and aggressive 3...d5, typically continuing with either 4.exd5 Qxd5 5.Nc3 Bb4 6.Bd2 Bxc3 7.Bxc3 Nc6 or with 4.Nbd2, which transposes to the 2.d3 line of Alekhine's Defence, are notable alternatives for Black.

See also

  • List of chess openings
  • List of chess openings named after people

References

Bibliography

Further reading

  • Petrov's Defence Video and explanation
  • Petrov's defence (C42) – 365Chess.com ECO Games
  • Gary Lane on the Cochrane Gambit
  • Cochrane Gambit theory