Petrov's Defense: Three Knights Game

The Three Knights Game of the Petrov Defense (1.e4 e5 2.Nf3 Nf6 3.Nc3) is a quiet way for White to meet the Petrov. Instead of taking on e5 or playing d4, White simply defends e4 and develops.

The idea

White often plays 3.Nc3 to avoid the lines that are unique to the Petrov. Black's most common and best-regarded answer, 3...Nc6, transposes to the Four Knights Game. The same position can also arise from the Vienna Game after 1.e4 e5 2.Nc3 Nf6 3.Nf3.

Main lines

• 3...Nc6, transposing to the Four Knights Game.
• 3...Bb4, the main alternative. After 4.Nxe5 O-O 5.Be2 Re8 6.Nd3 Bxc3 7.dxc3 Nxe4 8.Nf4 d6 9.O-O, White has a slight advantage thanks to the bishop pair.
• The similar position with the black knight on c6 instead of f6 is the Three Knights Opening, which also usually leads to the Four Knights.

Strengths and weaknesses

Strengths

• White avoids the theory of the main Petrov lines.
• Simple, natural development.

Weaknesses

• Black can transpose at once to the well-known Four Knights Game with 3...Nc6.

Who should play it

The Three Knights Game suits White players who want to sidestep the Petrov and are happy to play the Four Knights Game.

The numbers

On Lichess White's lead shrinks as ratings rise: 51.9% against 43.8% under 1400, 50.3% against 45.5% at 1400–1799, 48.7% against 46.0% at 1800–2199 and 46.4% against 45.2% from 2200 up. In about 4,900 master games 51.3% were drawn; White won 29.9% and Black 18.8%.