Answers.Body: <p>Generally speaking, ...Bf5 is most dangerous when White's reply of Qb3 attacks both d5 and b7.  For instance, if there were a N on c3, White would win a pawn after, say, ...Qb6, Qxb6, axb6, cxd5, etc.</p>
  <p>There are, of course, many instances where this doesn't quite work out as well for White as one might expect. For example, here's a celebrated Capablanca simul loss against Sergei Prokofiev (the famous composer):</p>
  <p>(EDIT: it should be pointed out that this line is, in spite of the result, objectively quite bad for Black and not technically a &quot;Slav&quot;)</p>
  <pre><code>[FEN &quot;&quot;]
  [Event &quot;Simul, 24b&quot;]
  [Site &quot;St. Petersburg RUE&quot;]
  [Date &quot;1914.05.16&quot;]
  [EventDate &quot;?&quot;]
  [Round &quot;?&quot;]
  [Result &quot;0-1&quot;]
  [White &quot;Jose Raul Capablanca&quot;]
  [Black &quot;Sergei Prokofiev&quot;]
  [ECO &quot;D02&quot;]
  
  1.d4 d5 2.Nf3 Nf6 3.c4 Bf5 4.Qb3 Nc6 5.Qxb7 Na5 6.Qa6 Nxc4
  7.Nc3 e6? (7...Bc8) 8.e4 dxe4 9.Bxc4? (9. Ne5!) exf3 10.Qc6+ Nd7 11.g4 Bg6 12.Bg5
  Be7 13.Bxe7 Kxe7 14.O-O-O Re8 15.h4 h5 16.gxh5 Bxh5 17.Nb5 Kf8
  18.d5 Qf6 19.dxe6 (19.Qxd7 Qf4+) Ne5 20.Qc5+ Kg8 21.exf7+ Bxf7 22.Bxf7+ Qxf7
  23.Kb1 Rab8 24.Nxc7 Rbc8 25.Rc1 Re7 26.Qd6 Rexc7 27.Rxc7 Qxc7
  28.Qe6+ Kh8 29.a3 Qc2+ 30.Ka1 Nd3 31.Rb1 Nxf2 32.h5 Qc6 33.Qf5
  Ne4 34.Qxf3 Nd2 35.Qxc6 Rxc6 36.Rd1 Rc2 37.Rg1 Rc5 38.Rg6 Rxh5
  39.Ra6 Nb3+ 40.Ka2 Ra5 41.Rxa5 Nxa5 42.b4 g5 43.Kb2 g4 0-1
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-01-08T14:57:46.667Z
Answers.Text: The example game is not a Slav...
Answers.UserDisplayName: Evargalo
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-01-08T20:49:55.217Z
Answers.Text: True.  My point was only about White's Qb3 vis a vis ...Bf5 and the double attack on b7 and d5, a theme in many "Slav like" structures.   Also this opening could have easily transposed into a Slav (for instance, 4.Nc3 c6) had Capablanca not gone for Qb3 and Qxb7.
Answers.UserDisplayName: John Chernoff
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Answers.LastEditDate: 2024-01-08T21:01:07.497Z
Answers.UserDisplayName: John Chernoff
Answers.Body: <p>Here White has chosen a slow, Catalan-like development, and is less capable of exploiting the weakness of b7.</p>
  <p>Every move order has its own flavour but the weakness of b7 (and of the Black queenside light squares as a whole) varies whether White can play such moves as Nxd5, Bb5, Ne5 or even sometimes Bf4/Nb5/Rc1.</p>
  <p>Generally, Qb3 or cd5 followed by Qb3 as an answer to ...Bf5 is rarely annoying when the Nb1 is not developed yet.</p>
  <p>Indeed, 4...Bf5 is a main line after:</p>
  <ul>
  <li>1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3</li>
  <li>1.d4 d5 2.c4 c6 3.g3 Nf6 4.Bg2</li>
  </ul>
  <p>But is frowned upon after:</p>
  <ul>
  <li>1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.Nf3</li>
  <li>1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3</li>
  <li>1.Nf3 d5 2.c4 c6 3.e3 Nf6 4.Nc3</li>
  </ul>
  <p>A key tactical point is the intermediate check Nxf6 after Nxd5. Compare:</p>
  <p>1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3 Bf5?! 5.cd cd 6.Qb3 Qb6?! (Wojkiewicz played several times 6...Bc8, the best move given the circumstances, with a passive but tenable position) 7.Nxd5! Qxb3 8.Nxf6 ef6 9.ab3 +/-</p>
  <p>And</p>
  <p>1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3 Bf5!? 5.cd cd 6.Qb3 Qb6 and Black is ok.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
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Answers.LastEditDate: 2024-01-08T15:28:14.957Z
Answers.UserDisplayName: Evargalo
Body: <p>I've read that it can be a tempting pitfall for Black in the Slav Defense to play an early Bf5, as this results in a weakening of the b7 square, which White might punish with Qb3.  This is apparently the rationale for Black to play dxc4, controlling the b3 square.</p>
  <p>However, in a recent game, as Black on move 4, I had this position:</p>
  <pre><code>rnbqkb1r/pp2pppp/2p2n2/3p4/2PP4/6P1/PP2PPBP/RNBQK1NR b KQkq - 2 4
  </code></pre>
  <p>I played 4...dxc4, but it seems Stockfish considers this a slight inaccuracy after 5.Nf3.  Instead, Stockfish thinks 4...Bf5 is best, and if 5.Qb3 then 5...Qb6 and Black has completely equalized.</p>
  <p>My question, broadly, is when is Bf5 a good move for Black in the Slav, and when is it dangerous without a prior dxc4?  In my game, is part of the problem with 4...dxc4 that White has fianchettoed his bishop on g2, making it dangerous for Black to try to keep the pawn on c4 with 5...b5?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-01-08T07:48:02.580Z
Comments.Text: IMHO, unfortunately, this can only be answered position-by-position. (Chess is hard...and modern opening theory hyperconcrete.) For example, with the white bishop already on f4 and Black having played Bf5 *and* e6, Qb6 might be problematic due to c5 (Qxb3 axb3 and Black might suffer, I played lots of games with such a variant). In other positions, Qxb7 is simply too risky for White.
Comments.UserDisplayName: Hauke Reddmann
Tags: <opening><slav-defense>
Title: Bf5 in the Slav
ThreadText: # Bf5 in the Slav
  
  (Asked by: username_0 on 2024-01-07)
  
  I've read that it can be a tempting pitfall for Black in the Slav Defense to play an early Bf5, as this results in a weakening of the b7 square, which White might punish with Qb3. This is apparently the rationale for Black to play dxc4, controlling the b3 square.
  
  However, in a recent game, as Black on move 4, I had this position:
  
  ```
  rnbqkb1r/pp2pppp/2p2n2/3p4/2PP4/6P1/PP2PPBP/RNBQK1NR b KQkq - 2 4
  
  ```
  
  I played 4...dxc4, but it seems Stockfish considers this a slight inaccuracy after 5.Nf3. Instead, Stockfish thinks 4...Bf5 is best, and if 5.Qb3 then 5...Qb6 and Black has completely equalized.
  
  My question, broadly, is when is Bf5 a good move for Black in the Slav, and when is it dangerous without a prior dxc4? In my game, is part of the problem with 4...dxc4 that White has fianchettoed his bishop on g2, making it dangerous for Black to try to keep the pawn on c4 with 5...b5?
  
  **Tags:** opening, slav-defense
  
  > **Comments:**
  > **username_1**: IMHO, unfortunately, this can only be answered position-by-position. (Chess is hard...and modern opening theory hyperconcrete.) For example, with the white bishop already on f4 and Black having played Bf5 *and* e6, Qb6 might be problematic due to c5 (Qxb3 axb3 and Black might suffer, I played lots of games with such a variant). In other positions, Qxb7 is simply too risky for White.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2024-01-08. Score: 5 | Accepted answer
  
  Here White has chosen a slow, Catalan-like development, and is less capable of exploiting the weakness of b7.
  
  Every move order has its own flavour but the weakness of b7 (and of the Black queenside light squares as a whole) varies whether White can play such moves as Nxd5, Bb5, Ne5 or even sometimes Bf4/Nb5/Rc1.
  
  Generally, Qb3 or cd5 followed by Qb3 as an answer to ...Bf5 is rarely annoying when the Nb1 is not developed yet.
  
  Indeed, 4...Bf5 is a main line after:
  
  * 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3
  * 1.d4 d5 2.c4 c6 3.g3 Nf6 4.Bg2
  
  But is frowned upon after:
  
  * 1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.Nf3
  * 1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3
  * 1.Nf3 d5 2.c4 c6 3.e3 Nf6 4.Nc3
  
  A key tactical point is the intermediate check Nxf6 after Nxd5. Compare:
  
  1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.e3 Bf5?! 5.cd cd 6.Qb3 Qb6?! (Wojkiewicz played several times 6...Bc8, the best move given the circumstances, with a passive but tenable position) 7.Nxd5! Qxb3 8.Nxf6 ef6 9.ab3 +/-
  
  And
  
  1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3 Bf5!? 5.cd cd 6.Qb3 Qb6 and Black is ok.
  
  
  ---
  
  ### Answer by username_2 on 2024-01-08. Score: 2
  
  Generally speaking, ...Bf5 is most dangerous when White's reply of Qb3 attacks both d5 and b7. For instance, if there were a N on c3, White would win a pawn after, say, ...Qb6, Qxb6, axb6, cxd5, etc.
  
  There are, of course, many instances where this doesn't quite work out as well for White as one might expect. For example, here's a celebrated Capablanca simul loss against Sergei Prokofiev (the famous composer):
  
  (EDIT: it should be pointed out that this line is, in spite of the result, objectively quite bad for Black and not technically a "Slav")
  
  ```
  [FEN ""]
  [Event "Simul, 24b"]
  [Site "St. Petersburg RUE"]
  [Date "1914.05.16"]
  [EventDate "?"]
  [Round "?"]
  [Result "0-1"]
  [White "Jose Raul Capablanca"]
  [Black "Sergei Prokofiev"]
  [ECO "D02"]
  
  1.d4 d5 2.Nf3 Nf6 3.c4 Bf5 4.Qb3 Nc6 5.Qxb7 Na5 6.Qa6 Nxc4
  7.Nc3 e6? (7...Bc8) 8.e4 dxe4 9.Bxc4? (9. Ne5!) exf3 10.Qc6+ Nd7 11.g4 Bg6 12.Bg5
  Be7 13.Bxe7 Kxe7 14.O-O-O Re8 15.h4 h5 16.gxh5 Bxh5 17.Nb5 Kf8
  18.d5 Qf6 19.dxe6 (19.Qxd7 Qf4+) Ne5 20.Qc5+ Kg8 21.exf7+ Bxf7 22.Bxf7+ Qxf7
  23.Kb1 Rab8 24.Nxc7 Rbc8 25.Rc1 Re7 26.Qd6 Rexc7 27.Rxc7 Qxc7
  28.Qe6+ Kh8 29.a3 Qc2+ 30.Ka1 Nd3 31.Rb1 Nxf2 32.h5 Qc6 33.Qf5
  Ne4 34.Qxf3 Nd2 35.Qxc6 Rxc6 36.Rd1 Rc2 37.Rg1 Rc5 38.Rg6 Rxh5
  39.Ra6 Nb3+ 40.Ka2 Ra5 41.Rxa5 Nxa5 42.b4 g5 43.Kb2 g4 0-1
  
  ```
  
  > **Comments:**
  > **username_3**: The example game is not a Slav...  
  > **username_2**: True.  My point was only about White's Qb3 vis a vis ...Bf5 and the double attack on b7 and d5, a theme in many "Slav like" structures.   Also this opening could have easily transposed into a Slav (for instance, 4.Nc3 c6) had Capablanca not gone for Qb3 and Qxb7.  
  
  ---
  
  