Answers.Body: <blockquote>
    <p>Why Black play Ra8 in this situation?</p>
  </blockquote>
  
  <p>He wanted to trap the White queen.</p>
  
  <blockquote>
    <p>I think it's better not to leave the queen unprotected.</p>
  </blockquote>
  
  <p>You are correct, Black made a blunder, and now loses the game: </p>
  
  <pre><code>[StartFlipped "0"]
  [fen "2r1k2r/Qbq1bppp/1pn1p3/1Bp1N3/3PP3/P1P5/5PPP/R1B1K2R b - - 0 1"]
  
  1...Ra8 2.Bxc6++- Qxc6 ( 2...Bxc6 3.Qxc7+-) 3.Nxc6! Rxa7 ( 3...Bxc6 4.Qxb6+- ) 4.Nxa7+-
  </code></pre>
  
  <p>Your question is not entirely clear but I hope this post answers it. If you need help or you have further questions leave a comment.</p>
  
  <h2>EDITED IN RESPONSE TO THE OP EDIT:</h2>
  
  <blockquote>
    <p>The point is why is Nc6 a bad move?</p>
  </blockquote>
  
  <p><code>Nc6</code> is a bad move because it allows <strong>a decisive pin</strong> along the <code>a4-e8</code> diagonal. The fact is that <code>Bb7</code> is badly posted to defend the knight on <code>c6</code>. If he were at <code>d7</code> then <code>Nc6</code> would not be pined and Black would be fine.</p>
  
  <p>After <code>Nc6</code> White is able to exploit the bad positioning of the <code>Bb7</code> to net himself a pawn on <code>a7</code>, <strong>and still keep the pressure on <code>Nc6</code>.</strong> After White captures on <code>a7</code> we have <strong>the second pin on <code>Qc7</code></strong> which paralyses Black. Now he must castle, but then White can win a piece:</p>
  
  <pre><code>[StartFlipped "0"]
  [fen "2r1k2r/Qbq1bppp/1pn1p3/1Bp1N3/3PP3/P1P5/5PPP/R1B1K2R b - - 0 1"]
  
  1...O-O 2.Bxc6 Bxc6 3.Nxc6! Qxc6 4.Qxe7 $18 Qxe4+ ( 4...cxd4 5.O-O ) 5.Be3 Qxg2 ( 5...cxd4 6.cxd4 Qxg2 ( 6...Qd3 7.Rd1 $18 ) 7.Kd2 $18 ) 6.O-O-O $18
  </code></pre>
  
  <p>I have checked the lines with the engine. If you have any doubts you can run these positions through the engine yourself. The point is that center is fixed, and White can defend himself by exchanging rooks on the <code>c-file</code>. Furthermore, bishop defends well too, and queen can come fast to defense. Black may be able to make a pressure <strong>but it will not be a permanent one.</strong> White will untangle eventually and convert his extra piece.</p>
  
  <p>If you still have doubts you can post the position as a new question and we can see if other members can spot something that I did not.</p>
  
  <h2>END OF EDIT</h2>
  
  <p>Hopefully this helped.</p>
  
  <p>Best regards.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-04-25T21:42:58.920Z
Answers.Text: Thank you for your reply. I do have further question, I edit my post and provide the context of the game. Seems I had asked the wrong question. The question is why Nc6 a bad move?
Answers.UserDisplayName: Rui
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2014-04-24T14:51:59.350Z
Answers.LastActivityDate: 2014-04-26T00:26:06.823Z
Answers.LastEditDate: 2014-04-26T00:26:06.823Z
Answers.UserDisplayName: AlwaysLearningNewStuff
Body: <p>I am reading <code>Kasparov Teaches Chess</code>, and I had a problem about this situation below:</p>
  
  <pre><code>[FEN "R2K1B1R/PPP5/5P1P/3PP3/3N1pB1/3p1np1/pppb1qbQ/r2k1r2 b - - 0 1"]
  </code></pre>
  
  <p>Black plays Ra8? next, why? I think it's better not to leave the queen unprotected.</p>
  
  <p><strong>Sorry I may not have made myself clear. Kasparov gives this variation to demonstrate a certain response is a bad move. I know Ra8 is bad. But if there aren't good choices, you can't say this variation is actually bad, isn't it?</strong></p>
  
  <p>This is the original board situation:</p>
  
  <pre><code>[FEN "rn1qk2r/pb2bppp/1p2p3/1Bp5/3PP3/P1P2N2/2Q2PPP/R1B1K2R b KQkq - 0 1"]
  
  1... Nc6 2.Ne5 Rc8 3.Qa4 Qc7 4.Qxa7 Ra8? 5.Bxc6+{White Wins}
  </code></pre>
  
  <p>And by giving such a variation Kasparov made a conclusion that Nc6 is a bad move. What if Black don't play Ra8? He can still possibly make equal trades, and thus Nc6 isn't really bad?</p>
  
  <p><strong>The point is, why is Nc6 a bad move?</strong></p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2014-04-24T11:57:07.573Z
Comments.Text: Are you sure Kasparov is not demonstrating why Ra8 is a bad move?  Black's in bad shape here.  Instead of Ra8, castling will help for multiple reasons including removing the pin on c6 and allowing the rooks to defend each other.
Comments.UserDisplayName: Tony Ennis
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-05-17T15:24:51.777Z
Comments.Text: @aschultz, Thank you for your edition, but I found a small fault:  In the bold string up, "if there **are** good choices, you can't say this variation is actually bad."
Comments.UserDisplayName: Rui
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-05-17T15:59:12.427Z
Comments.Text: @Rui glad I could help and sorry for that oversight! I think my brain must've registered that the sentence was a double negative, which it wasn't.
Comments.UserDisplayName: aschultz
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-05-18T15:04:59.607Z
Comments.Text: @aschultz, yeah sometime I make mistake in code and can't really realize the bug, it's hard to avoid.
Comments.UserDisplayName: Rui
Tags: <analysis>
Title: Why did Black play Ra8 in this situation?
ThreadText: # Why did Black play Ra8 in this situation?
  
  (Asked by: username_0 on 2014-04-24)
  
  I am reading Kasparov Teaches Chess, and I had a problem about this situation below:
  [FEN "R2K1B1R/PPP5/5P1P/3PP3/3N1pB1/3p1np1/pppb1qbQ/r2k1r2 b - - 0 1"]
  
  Black plays Ra8? next, why? I think it's better not to leave the queen unprotected.
  Sorry I may not have made myself clear. Kasparov gives this variation to demonstrate a certain response is a bad move. I know Ra8 is bad. But if there aren't good choices, you can't say this variation is actually bad, isn't it?
  This is the original board situation:
  [FEN "rn1qk2r/pb2bppp/1p2p3/1Bp5/3PP3/P1P2N2/2Q2PPP/R1B1K2R b KQkq - 0 1"]
  
  1... Nc6 2.Ne5 Rc8 3.Qa4 Qc7 4.Qxa7 Ra8? 5.Bxc6+{White Wins}
  
  And by giving such a variation Kasparov made a conclusion that Nc6 is a bad move. What if Black don't play Ra8? He can still possibly make equal trades, and thus Nc6 isn't really bad?
  The point is, why is Nc6 a bad move?
  
  **Tags:** analysis
  
  > **Comments:**
  > **username_1**: Are you sure Kasparov is not demonstrating why Ra8 is a bad move?  Black's in bad shape here.  Instead of Ra8, castling will help for multiple reasons including removing the pin on c6 and allowing the rooks to defend each other.  
  > **username_0**: @username_2, Thank you for your edition, but I found a small fault:  In the bold string up, "if there **are** good choices, you can't say this variation is actually bad."  
  > **username_2**: @username_0 glad I could help and sorry for that oversight! I think my brain must've registered that the sentence was a double negative, which it wasn't.  
  > **username_0**: @username_2, yeah sometime I make mistake in code and can't really realize the bug, it's hard to avoid.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_3 on 2014-04-24. Score: 3 | Accepted answer
  
  Why Black play Ra8 in this situation?
  
  He wanted to trap the White queen.
  
  I think it's better not to leave the queen unprotected.
  
  You are correct, Black made a blunder, and now loses the game: 
  [StartFlipped "0"]
  [fen "2r1k2r/Qbq1bppp/1pn1p3/1Bp1N3/3PP3/P1P5/5PPP/R1B1K2R b - - 0 1"]
  
  1...Ra8 2.Bxc6++- Qxc6 ( 2...Bxc6 3.Qxc7+-) 3.Nxc6! Rxa7 ( 3...Bxc6 4.Qxb6+- ) 4.Nxa7+-
  
  Your question is not entirely clear but I hope this post answers it. If you need help or you have further questions leave a comment.
  EDITED IN RESPONSE TO THE OP EDIT:
  
  The point is why is Nc6 a bad move?
  
  Nc6 is a bad move because it allows a decisive pin along the a4-e8 diagonal. The fact is that Bb7 is badly posted to defend the knight on c6. If he were at d7 then Nc6 would not be pined and Black would be fine.
  After Nc6 White is able to exploit the bad positioning of the Bb7 to net himself a pawn on a7, and still keep the pressure on Nc6. After White captures on a7 we have the second pin on Qc7 which paralyses Black. Now he must castle, but then White can win a piece:
  [StartFlipped "0"]
  [fen "2r1k2r/Qbq1bppp/1pn1p3/1Bp1N3/3PP3/P1P5/5PPP/R1B1K2R b - - 0 1"]
  
  1...O-O 2.Bxc6 Bxc6 3.Nxc6! Qxc6 4.Qxe7 $18 Qxe4+ ( 4...cxd4 5.O-O ) 5.Be3 Qxg2 ( 5...cxd4 6.cxd4 Qxg2 ( 6...Qd3 7.Rd1 $18 ) 7.Kd2 $18 ) 6.O-O-O $18
  
  I have checked the lines with the engine. If you have any doubts you can run these positions through the engine yourself. The point is that center is fixed, and White can defend himself by exchanging rooks on the c-file. Furthermore, bishop defends well too, and queen can come fast to defense. Black may be able to make a pressure but it will not be a permanent one. White will untangle eventually and convert his extra piece.
  If you still have doubts you can post the position as a new question and we can see if other members can spot something that I did not.
  END OF EDIT
  Hopefully this helped.
  Best regards.
  
  > **Comments:**
  > **username_0**: Thank you for your reply. I do have further question, I edit my post and provide the context of the game. Seems I had asked the wrong question. The question is why Nc6 a bad move?  
  
  ---
  
  