his position comes from the game 
Joel Johnson (2205) vs Fermin Arias (1920), ICC tourney 1230 (3 2), Round 7, played February 20, 2017 . 

 

   In the position on the right it is Black to move. 

 

   Answer below.

   In Greek mythology, when Achilles was a baby, it was foretold that he would die young.

   To prevent his death, his mother Thetis took Achilles to the River Styx, which was supposed to offer powers of invulnerability, and dipped his body into the water; however, as Thetis held Achilles by the heel, his heel was not washed over by the water of the magical river.

   Achilles grew up to be a man of war who survived many great battles.

   One day, a poisonous arrow shot at him was lodged in his heel, killing him shortly afterwards.

   The moral of the story is: all it takes is a single weakness to bring down any chess player, no matter how powerful they may appear.


   Here is the complete game:

[Event "ICC tourney 1230 (3 2)"]
[Site "Internet Chess Club"]
[Date "2017.02.20"]
[Round "7"]
[White "Arias, Fermin"]
[Black "Johnson, Joel"]
[Result "0-1"]
[ECO "B00"]
[WhiteElo "1920"]
[BlackElo "2205"]
[PlyCount "56"]
[EventDate "2017.??.??"]
1. d4 b5 2. e4 a6 3. f4 Bb7 4. Bd3 Nf6 5. Nd2 e6 6. Ngf3 c5 7. c3 Qb6 8. e5 Nd5
9. Ne4 cxd4 10. cxd4 Nc6 11. Bc2 Rc8 12. a3 f6 13. O-O b4 14. exf6 gxf6 15. Kh1
f5 16. Neg5 h6 17. Nh3 Bg7 18. Ne5 Bxe5 19. Qh5+ Kd8 20. fxe5 Nxd4 21. Bd3 Kc7
22. Nf4 Nxf4 23. Bxf4 Rhg8 24. Rac1+ Kb8 25. Rxc8+ Kxc8 26. Rc1+ Kb8 27. Bf1
Nf3 28. Qf7 Qg1# 0-1

   You can play through this game here: http://view.chessbase.com/cbreader/2017/7/4/Game784294218.html

 

   Answer:  

   27...Nf3! threatening 28...Qg1#. 

   If 28.gxf3 Rg1# (or 28...Qg1#)

   If White moves the bishop, with a move like 28.Bd3, Black gangs up on the g2 pawn with 28...Nh4 or 28...Ne1 unleashing the powerful combination of the rook and bishop.

   A master level player can quickly identify the weak squares around the White King.

   The weak square g1 just pops off the board as a glaring weak square with only the White King protecting that square.

   From there, we can look for different ways to attack the weak square.

   Just remember one weak square in your opponent’s defensive stronghold can induce a terminal attack.

   The ability to manufacture and/or identify existing weaknesses in your opponent’s position is a lethal skill to possess. 
 

 

   Happy Tactics!

 

   Your Friend,
 

  Joel

   Life Master Joel Johnson
   2007 U.S. Senior Champion
   Author of “Formation Attacks”, “Formation Attack Strategies”, “Positional Attacks”, and Attacking 101: Volumes #001-#004. All of my attack books are available at http://www.lulu.com/spotlight/fearnoevil