Petrov's Defense: Three Knights Game

Against Petrov's Defense, White does not have to consent to the exchange of the e-pawns - instead, he can protect his own e4 pawn by 3.Nc3. If Black responds with 3...Nc6 it will lead to the Four Knights Game; but Black can also play 3...Bb4, aiming to put more pressure on e4 and castle quickly.

Pros:

• White avoids the heavily-analyzed Petrov's Defense
• White avoids simplification
• Nc3 defends the e-pawn without blocking in the bishop (e.g. 3.d3)

Cons:

• Black can transpose to the Four Knights Game
• White blocks the c-pawn, which could be used to fight for the center