A Larsen shot

Stealing yet again from Yakov Neistadt's Improve Your Chess Tactics (New in Chess, 2011).

Like Petrosian, Bent Larsen was best known as a positional player.  But he too was an outstanding tactician, and in his wonder year 1967, he didn't miss too many shots.

Black has some chances in the knight ending, but does he need to make the game last that long?

Westerinen-Larsen, Havana 1967

Black to play and win