Rusa o Petrov

After 2.Nf3 Black is in no way obliged to defend his e-pawn. Instead, he can play 2...Nf6 and start a counter-attack against White’s e-pawn. In the 19th century the Russian players Alexander Petroff (1794–1867) and Carl Friedrich Jänisch (1813–1872) made important contributions to the development of the variation, which has therefore become known as the Petroff Defence (or the Russian Defence).

In the second half of the 20th century after a long period of neglect, it developed in the 1980s into one of the most reliable ways for Black to achieve a draw at the top level. Worldclass players such as Karpov, Yusupov, Gelfand, Kramnik and Anand adopted it as part of their repertoire and the question as to how White could manage to reach an advantage against the Petroff became an even more ticklish one.