As I’m currently writing a book for Everyman Chess on a Nimzo and Queen’s Indian repertoire the Nimzo was an obvious choice for N. Some of you might have expected the Najdorf but I prefer not to encourage highly theoretical lines in which the maintenance load increases as players move up the rankings.
The Nimzo-Indian (1.d4 Nf6 2.c4 e6 3.Nc3 Bb4) can be played largely using themes and concepts rather than an exact knowledge of theory, and as such it gets my approval. It was developed as a means of preventing White from building a broad pawn center with e2-e4 but without Black physically occupying the center himself via 3…d7-d5. It was largely pioneered by Aron Nimzowitsch whose name it partly borrows, 1…Nf6 once having been referred to as the Indian Defence rather than the classical 1…d5. Nimzowitsch was the first player to fully realize its potential, especially the potential weakness of White’s doubled c-pawns. Here is an early game in which his opponent was very much at sea and lost without a struggle:
The Nimzo-Indian has evolved considerably since this time with the critical lines being regarded as 4.Qc2, 4.e3 and 4.f3. Here’s a highly dramatic encounter from the match in which Magnus Carlsen seized the World Championship title; subsequent engine analysis showed that White’s attack was really very strong.
In my book I’ll be recommending 4…c5 instead of 4…d5, with doubled pawns arising after 5.d5 d6 6.e4 Bxc3+.