NimzoIndian - Leningrad Variation

The Leningrad (perhaps we should call it St Petersburg) variation of the NimzoIndian (1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Bg5) was a favorite of Boris Spassky (from Leningrad).  It was also played by Alekhine,Reti, and Korchnoi.  This game, from the Nice Chess Olympiad in 1974, featured a rook sacrifice that opened up Black's position.  White eventually had enough attack to force checkmate.