Answers.Body: <p>I am tempted to say "agreeing to continue the match after Fischer's protests!" which some argue was a key psychological defeat.  If you're looking for specific moves that were mistakes, there are a few candidates.  I haven't looked at all annotations, but have Kasparov's <em>My Great Predecessors, vol 4</em> handy and looking over his notes, it would be either (notations and comments are his):</p>
  
  <ol start="20">
  <li>...d4?
  "This move, conceding the important c4-square, was rightly condemned by the commentators.  20. ...Nf6 really was better...but the most accurate solution was the continuation 20. ...c4"</li>
  </ol>
  
  <p>and</p>
  
  <ol start="22">
  <li>...Rb8?!
  "The last critical moment."</li>
  </ol>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-02-11T20:59:04.540Z
Answers.LastActivityDate: 2016-02-11T20:59:04.540Z
Answers.UserDisplayName: rougon
Answers.Body: <p>The biggest was 36...Qe8. Other than that, 20...d4 and maybe 18...Qf8 could be called "weak" if not outright "blunder".</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-02-11T20:59:14.183Z
Answers.LastActivityDate: 2016-02-11T20:59:14.183Z
Answers.UserDisplayName: Jeff Y
Body: <p>I just wanted to inquire about the biggest mistake or blunder by Boris Spassky In game no. 6 against Bobby Fischer.</p>
  
Tags: <world-championship><famous-players><blunder><famous-moves>
Title: What was the biggest blunder made by Boris Spassky in Game 6?
ThreadText: # What was the biggest blunder made by Boris Spassky in Game 6?
  
  (Asked by: username_0 on 2016-02-11)
  
  I just wanted to inquire about the biggest mistake or blunder by Boris Spassky In game no. 6 against Bobby Fischer.
  
  **Tags:** world-championship, famous-players, blunder, famous-moves
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2016-02-11. Score: 1 | Accepted answer
  
  I am tempted to say "agreeing to continue the match after Fischer's protests!" which some argue was a key psychological defeat. If you're looking for specific moves that were mistakes, there are a few candidates. I haven't looked at all annotations, but have Kasparov's *My Great Predecessors, vol 4* handy and looking over his notes, it would be either (notations and comments are his):
  
  20. ...d4?
      "This move, conceding the important c4-square, was rightly condemned by the commentators. 20. ...Nf6 really was better...but the most accurate solution was the continuation 20. ...c4"
  
  and
  
  22. ...Rb8?!
      "The last critical moment."
  
  
  ---
  
  ### Answer by username_2 on 2016-02-11. Score: 0
  
  The biggest was 36...Qe8. Other than that, 20...d4 and maybe 18...Qf8 could be called "weak" if not outright "blunder".
  
  
  ---
  
  