Here is a nice tactical finish by the great
Petrosian.  He had a reputation as a methodical positional player but here he won in only 21 moves.
      Can you find the three moves that lead to
black's resignation?

Bonus 1: Can you explain why black resigned?
Bonus 2: Can you name Petrosian's opponent?

     Well, for some reason this puzzle is not working for me when I try it.

The moves are: 19. Qxf6+   Kxf6
                        20. Be5+    Kg5
                        21. Bg7

Looks like black's king is stuck on the 5th rank, and with white's pawns and light squared bishop/knight can get a checkmate quickly.

Ludek Pachman was his opponent.

Correct as usual.

unfortunately saw this game a week ago so I knew it :D