Answers.Body: <p>I think it's probably a mistake.</p>
  
  <p>I checked a database, and the position that arises after 5.Be2 only appeared in it twice - once in a game from way back in 1883, and once in a game between two  players rated 2600+ in a 2011 rapid event.  5...d5 (rather than 5...d6) was played in both games, and Black won both.</p>
  
  <p>If the double pawn move isn't a mistake, then we can assume that White's intervening move, 6.Nc3, somehow changed the position to make d5 more favorable.  So how did Nc3 change the position?  </p>
  
  <ul>
  <li>The knight prevents White from playing c4 to challenge a pawn on d5.  </li>
  <li>The knight could be a target on c3 if Black later advances the pawn to d4.  </li>
  <li>White cannot now move the knight to a3 or d2.</li>
  </ul>
  
  <p>I'm not convinced.  Black never played d4 in the line you showed, and c4 doesn't look like it's something to be feared.  And I don't see any reason why White playing Na3 or Nbd2 would make d5 less favorable.</p>
  
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Answers.CreationDate: 2018-06-06T03:03:41.777Z
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Answers.Body: <p>I checked the position on Stockfish and its 1st or 2nd recommendation is to play 6...d5 after 6.Nc3, so your Chessable opening line is sound.</p>
  
  <p>The reason for playing 6...d5 is that White's c3-knight is misplaced. If you were to attack it by pushing ...d4, it doesn't have a good square to move to (normally, it would like to move to e2 but a bishop is sitting there).</p>
  
  <p>The reason for not playing 5...d5 on the fifth move is that White doesn't have to bring his knight to c3. Instead, he can move it to d2, where it won't be attacked by your pawn.</p>
  
  <p>In the line you posted, I think White went for the stuff with 8.e5 and 9.d4 in order to prevent Black from playing ...d4 at an opportune moment. The pawn structure that arose after 9.d4 is favorable for Black, since White's missing his centre pawn.</p>
  
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Answers.UserDisplayName: Inertial Ignorance
Answers.Body: <p>Definitely not a good chessable line.<br>
  If the idea is to play d5 then 5...d5 saves a tempo.  It's not like White has altered his position in a way that makes 6...d5 more desirable. 
  The line you gave is slightly to clearly better for White as Black has a bad Bc8 and less space.  </p>
  
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Answers.UserDisplayName: Ywapom
Body: <p>I was going through a <a href="https://www.chessable.com/practice/book/1338" rel="nofollow noreferrer">Chessable opening line</a>, and it recommends black to play <code>6...d5</code>, moving the d pawn immediately after it was <em>just moved</em> in <code>5...d6 6.Nc3</code>.</p>
  
  <p>What is the reason behind moving the same pawn twice?</p>
  
  <pre><code>[FEN "r1bqk1nr/pp2bppp/2npp3/2p5/4PP2/2NP1N2/PPP1B1PP/R1BQK2R b KQkq - 1 6"]
  
  6... d5 7. O-O Nf6 8. e5 Nd7 9. d4 cxd4 10. Nb5 O-O 11. Nbxd4 Nxd4 12. Nxd4 Nc5
  </code></pre>
  
  <p>Full line here:</p>
  
  <pre><code>[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 c5 2. f4 Nc6 3. Nf3 e6 4. d3 Be7
  5. Be2 d6 6. Nc3 d5?? 7. O-O Nf6 8. e5 Nd7
  9. d4 cxd4 10. Nb5 O-O 11. Nbxd4 Nxd4 12. Nxd4 Nc5
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-06-06T05:55:06.280Z
Comments.Text: Are recommended moves determined by database statistics? If so, it might be a mix-up of transpositions.
Comments.UserDisplayName: Annatar
Tags: <opening><sicilian-defense>
Title: Strange pawn double move in McDonnell attack
ThreadText: # Strange pawn double move in McDonnell attack
  
  (Asked by: username_0 on 2018-06-06)
  
  I was going through a Chessable opening line, and it recommends black to play 6...d5, moving the d pawn immediately after it was just moved in 5...d6 6.Nc3.
  What is the reason behind moving the same pawn twice?
  [FEN "r1bqk1nr/pp2bppp/2npp3/2p5/4PP2/2NP1N2/PPP1B1PP/R1BQK2R b KQkq - 1 6"]
  
  6... d5 7. O-O Nf6 8. e5 Nd7 9. d4 cxd4 10. Nb5 O-O 11. Nbxd4 Nxd4 12. Nxd4 Nc5
  
  Full line here:
  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
  1. e4 c5 2. f4 Nc6 3. Nf3 e6 4. d3 Be7
  5. Be2 d6 6. Nc3 d5?? 7. O-O Nf6 8. e5 Nd7
  9. d4 cxd4 10. Nb5 O-O 11. Nbxd4 Nxd4 12. Nxd4 Nc5
  
  **Tags:** opening, sicilian-defense
  
  > **Comments:**
  > **username_1**: Are recommended moves determined by database statistics? If so, it might be a mix-up of transpositions.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_2 on 2018-06-06. Score: 3 | Accepted answer
  
  I think it's probably a mistake.
  
  I checked a database, and the position that arises after 5.Be2 only appeared in it twice - once in a game from way back in 1883, and once in a game between two players rated 2600+ in a 2011 rapid event. 5...d5 (rather than 5...d6) was played in both games, and Black won both.
  
  If the double pawn move isn't a mistake, then we can assume that White's intervening move, 6.Nc3, somehow changed the position to make d5 more favorable. So how did Nc3 change the position?
  
  * The knight prevents White from playing c4 to challenge a pawn on d5.
  * The knight could be a target on c3 if Black later advances the pawn to d4.
  * White cannot now move the knight to a3 or d2.
  
  I'm not convinced. Black never played d4 in the line you showed, and c4 doesn't look like it's something to be feared. And I don't see any reason why White playing Na3 or Nbd2 would make d5 less favorable.
  
  
  ---
  
  ### Answer by username_3 on 2018-06-06. Score: 3
  
  I checked the position on Stockfish and its 1st or 2nd recommendation is to play 6...d5 after 6.Nc3, so your Chessable opening line is sound.
  
  The reason for playing 6...d5 is that White's c3-knight is misplaced. If you were to attack it by pushing ...d4, it doesn't have a good square to move to (normally, it would like to move to e2 but a bishop is sitting there).
  
  The reason for not playing 5...d5 on the fifth move is that White doesn't have to bring his knight to c3. Instead, he can move it to d2, where it won't be attacked by your pawn.
  
  In the line you posted, I think White went for the stuff with 8.e5 and 9.d4 in order to prevent Black from playing ...d4 at an opportune moment. The pawn structure that arose after 9.d4 is favorable for Black, since White's missing his centre pawn.
  
  
  ---
  
  ### Answer by username_4 on 2018-06-07. Score: 0
  
  Definitely not a good chessable line.  
  If the idea is to play d5 then 5...d5 saves a tempo. It's not like White has altered his position in a way that makes 6...d5 more desirable.
  The line you gave is slightly to clearly better for White as Black has a bad Bc8 and less space.
  
  
  ---
  
  