Funny positional piece sacrifice

[Nordlandia]

Key move 1...Nb3!

The bishop is under lock and key.

[d]r2qk2r/3bbppp/3p1n2/n1pNp3/1p2P3/3P1N1P/BPP2PP1/R1BQ1RK1 b kq - 0 1

[pgn][Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "New game"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "r2qk2r/3bbppp/3p1n2/n1pNp3/1p2P3/3P1N1P/BPP2PP1/R1BQ1RK1 b kq - 0 1"]
[PlyCount "5"]

{[#]} 1... Nb3 2. cxb3 Nxd5 3. exd5 O-O *[/pgn]

New game Line
r2q1rk1/3bbppp/3p4/2pPp3/1p6/1P1P1N1P/BP3PP1/R1BQ1RK1 w - - 0 1

Analysis by Lc0 v0.26.3: | 2x 2080 Super Overclock

4.Nd2 Ra6 5.f4 exf4 6.d4 Bf6 7.Nf3 Bb5 8.Re1 cxd4 9.Kh2 Qa8 10.Nxd4 Qxd5 11.Nxb5 Qxb5 12.Bxf4 Rfa8 13.Qd2 h5 14.Bxd6 Rxa2 15.Rxa2 Rxa2 16.Qxb4 Qxb4 17.Bxb4 Rxb2 18.Re3 Bd4 19.Rd3 Bf2 20.Rd2 Rxb3 21.Rxf2 Rxb4 22.Rf5 h4 23.Rf3
The position is equal: = (-0.01) Depth: 18/44 00:00:35 558kN
(15.10.2020)

[Ajedrecista]

Hello:

Does this position come from a real game? The best I could work by myself with not many suboptimal moves is the following ECO C84 line:

[pgn][Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[PlyCount "25"]

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. d3 b5 7. Bb3 d6 8. a4 Bd7 9. h3 Na5 10. Ba2 c5 11. axb5 axb5 12. Nc3 b4 13. Nd5[/pgn]

The white bishop can only be defended at some point with either Qb1 (rook traped on a1) or Nc1 (rook available squares only at a1 and b1) while black controls the a-column with the rook in a natural way. 13.- ..., Nb3 is a nice move indeed! 14.- Nxf6+ is still possible and white does not need to double pawns on d-column, although the resultant position might be worse if white does not play d4 soon according with brief SF 12 analysis.

Regards from Spain.

Ajedrecista.

[peter]

Key move 1...Nb3!

That's true, Jon, yet the black Knight is gone.

For sure it's one of the moves to be considered here, in Hiarcs14j.ctg (October update of subscription-book) there's ...Nxd5 only but with !?.

Cfish takes some time to bring it to first place in MultiPV=3, but after a little backward of your follow- up moves in depth 35 with Use NNUE Pure, it starts sticking to it (more or less constantly, with some short changes back to ...Nxd5 now and then once in a while)

Here's depth 48/63:

r2qk2r/3bbppp/3p1n2/n1pNp3/1p2P3/3P1N1P/BPP2PP1/R1BQ1RK1 b kq - 0 1

Analysis by CF EXT 041020 x64 SSE41 N:

1. = (0.00): 13...Nb3 14.cxb3 Nxd5 15.exd5 0-0 16.Re1 f5 17.Bd2 Bb5 18.d4 e4 19.Nh2 Bd3 20.Re3 Bb5

2. = (0.22): 13...Nxd5 14.Bxd5 Bc6 15.c4 Bf6 16.Be3 0-0 17.Nd2 Bb7 18.Qg4 Qe7 19.Ra4 Nc6 20.Rfa1 Rxa4 21.Rxa4 Qc7 22.Qf3 Ne7 23.Qd1 Nc6 24.Qa1 Be7 25.b3 Bd8 26.Ra2 Bf6 27.Qd1 Rb8 28.Qf3 Rf8 29.Qh5 Be7 30.Qd1 Bf6 31.Qa1 Rb8 32.Ra4 Qd7 33.Qd1 Rf8 34.Qh5 Qc7 35.Nf1 Ne7 36.Ra7 Nc6 37.Ra2 Ne7 38.Bxb7 Qxb7

3. = (0.25): 13...0-0 14.c3 bxc3 15.bxc3 Bc6 16.Nxf6+ Bxf6 17.Re1 h6 18.Be3 c4 19.Qe2 Nb3 20.Bxb3 cxb3 21.Nd2 d5 22.Bc5 Rxa1 23.Rxa1 Re8 24.Nxb3 Qb8 25.Ra6 Qxb3 26.Rxc6 dxe4 27.dxe4 Qxc3 28.Kh2 Rd8 29.Qg4 Qc1 30.g3 Qe1 31.Rc8 Rxc8 32.Qxc8+ Kh7 33.Qf5+ Kg8 34.h4 h5 35.Qxh5 Qxe4 36.Be3 Qg6 37.Qxg6 fxg6 38.h5 Kh7 39.hxg6+ Kxg6

Good found of yours, even if a line leading to this won't be played very oftenly, didn't find a single game at chessbase online with Ajedrecista's opening moves after 13.Nd5.

[Nordlandia]

Possible continuation in the Carlsen Tari game.

See ->

[peter]

Possible continuation in the Carlsen Tari game.

See ->

I see, if I got Judith Polgar right, it was something somebody showed to her once in while before as an idea of LC0, as for the side line with ...Nb3.
In the game h3 wasn't played, c3 instead of Nc3 e.g.
Found another one YouTube to the game:

[Ajedrecista]

Hello:

Possible continuation in the Carlsen Tari game.

See ->

Thank you for the source. Answering Peter, my intention was giving a sequence of moves that reaches the position although any transposition of the sequence could be valid, so my line was a proposed line whose moves where suitable of change in order. The order of moves given in the video is the same than my proposal until 8.- ..., Bd7. Then: 9.- Nc3, Na5; 10.- axb5, axb5; 11.- Ba2, c5; 12.- h3 returning to my proposal.

I found other YouTube review of 23 minutes (Good Knight vs Bad Bishop | Carlsen vs Tari | Altibox Norway Chess, Stavanger 2020) thanks to a comment at the Chessgames page dedicated to the game.

Looking at the actual game: 33.- ..., Qd7 seems the only chance to fight for a draw, but 33.- ..., Rc7? was played instead. The finish of the game was smart.

Regards from Spain.

Ajedrecista.