C42 Petroff Defence

ECO code C42 covers the Petroff Defence, also called the Russian Game, which begins 1.e4 e5 2.Nf3 Nf6. Instead of defending the e5-pawn, Black counter-attacks e4. The main line runs 3.Nxe5 d6 4.Nf3 Nxe4: 3...d6 first drives the knight back, so Black can win back the pawn safely. White then picks 5.d4 d5 6.Bd3, the Classical Attack, which targets the advanced knight on e4. Other choices are 5.Nc3, which offers a knight exchange, and 5.Qe2, which attacks along the e-file and often leads to an early queen trade. The code also includes 3.Nc3, the Three Knights, met here by 3...Bb4.