Petrov's Defense
Petrov's Defense (also spelled Petroff and alternatively called the Russian Game, Petrov Defense, or simply the Petrov) is one of Black's most solid options against 1.e4. On move two, Black responds to an attack on the e5 pawn by counterattacking the pawn on e4 with the knight. This often leads to a trade of pawns on the e-file.
Although often considered a drawish opening for this reason among others, in the last several years players like GM Fabiano Caruana have shown it to have much more bite than previously thought. That said, it remains a less dynamic opening than many others.
Starting Position
Petrov's Defense begins 1.e4 e5 2.Nf3 Nf6. The main independent lines of the Petrov are 3.Nxe5 and 3.d4. Also possible on move three is 3.Nc3, which transposes into the Four Knights Game.
Pros
- Black develops rapidly
- Very sound
- Solid defense
Cons
- In the open positions that result, White has a slight development lead
- White has some very drawish options
- There is a lot of theory in some lines
Key Variations
The Petrov almost always continues 3...d6 4.Nf3 Nxe4 at which point White has two main options.
Classical Attack
The older and still most common continuation is 5.d4 d5 6.Bd3 at which point Black has several options: 6...Be7, 6...Bd6, 6...Nc6 are most common. Both sides develop quickly and strategic play usually ensues.
Nimzowitsch Attack
In recent years, White has started playing 5.Nc3 on move five, welcoming doubled pawns in exchange for quick development after 5...Nxc3 6.dxc3. White usually castles queenside while Black, after the best and most common follow-up, 6...Be7, can either castle short or wait in the center and develop the queenside.
Black can blunder in this line if not careful, and no less than GM Viswanathan Anand did so in 1988 by, instead of taking the knight on c3, going for 5...Bf5 6.Qe2, at which point he resigned because 6...Qe7 7.Nd5 loses at least a piece for Black.
Traps and Sidelines
It is tempting for less experienced players to try to retain symmetry with 3...Nxe4 instead of 3...d6, but this move loses at least a pawn, and often more than that if Black isn't careful.
A sideline of Petrov's Defense that has become popular in online blitz in recent times is the Stafford Gambit, which is 3...Nc6 on move three. More information on the Stafford is available here.
5.Qe2 is another playable fifth move for White, but it leads to a draw in four out of every five master-level games. In most situations White is playing for some kind of advantage in the opening, which this move does not achieve, but if White only needs a draw the move can be useful.
History
Petrov's Defense is named for the 19th century Russian master Alexander Petrov, although it was a known opening well before his time, appearing in the work of Pedro Damiano around the year 1500.
The move 2...Nf6 was long used as a drawing weapon when the player with the black pieces did not want to face the complexities that follow 2...Nc6. Although generally considered a respectable opening, it did not appear in a world chess championship until 1969 when GM Tigran Petrosian made a couple quick draws with it in a match he eventually lost to GM Boris Spassky.
About 50 years later, Caruana used it all three times he faced 1.e4 as Black in the 2018 Candidates, and all three games were decisive including two wins. Caruana has also shown how White can beat the Petrov, as GM Greg Serper explained in this 2019 piece. Unless White is happy with a draw before the game even begins, the Petrov is nonetheless a strong opening for Black.