Pawn to j6!

This is the Half Queenside Petroff opening. It usually leads to complex middlegame positions where either tactics or strategy can dominate, so it's very difficult to anticipate how your opponent will proceed, no matter which color one has! In this game we see how quickly the tide can change. White's strong attack at 18. Ai5 is stymied by the intermezzo 21...j6! and the momentum shifts in favor of black. With 25...Rh4! black has made his tangible positional advantage felt and white must again retreat. Black actually gets to play Nh4! twice with28...Nh4! and 35...Nh4! one time hitting the white Queen and the other striking at his Chancellor. The combination 36. hxi4 Nxi2 37. Rxh8+ Rxh8 38. Kxi2 Rh2+ is what Bobby Fischer would refer to as the tail of the scorpion when annotating his own 8x8 chess games. White appears to be facing an unstoppable checkmate after 40...Cxi4 but the surprise 41. Qi1! is a tactical save worthy of study.