The variation is almost forced if White aims for the standard Smith-Morra setup. At the end White is a pawn down and no longer has two bishops, but is well developed. However Black's setup does not seem to have any weaknesses that can be pressured by White's superior pieces.

White's most immediate plan is to strike on the flank with a4, provoking ...b4.

In most of games at 2000+ level, White ends up defending a worse endgame.

 [fen ""] 
 1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 e6
 5. Nf3 Nc6 6. Bc4 a6 7. O-O b5 8. Bb3 Na5
 9. Re1 Nxb3 10. Qxb3

If Black reveals his intention to play ...a6 early, White has alternative plans: Play Bf4, threatening Nd5 with pressure on the dark squares c7, d6 and b6, leading to decent games with White retaining the initiative. So Black should delay ...a6 as much as he can, as Bf4 only makes sense after ...a6.

[fen ""]
1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 Nc6
5. Nf3 a6 6. Bf4 e6 7. Be2

Also, ...Na5 needs to be played immediately, as 8...Bb7 allows 9. a4 with initiative and nasty tricks from White. Example game:

[fen ""] 
[White "Vivante-Sowter, John (2259)"]
[Black "Kavc, Andrej (2270)"]

1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 e6 5. Nf3 a6 { B21 Sicilian Defense: Smith-Morra Gambit Accepted, Kan Formation } 6. Bc4 b5 7. Bb3 Bb7 8. O-O Nc6 9. a4 b4 10. Nd5 Na5 11. Bg5 f6 12. Ne5 Bxd5 13. exd5 Nxb3 14. dxe6 dxe6 15. Qxb3 Qd5 16. Nc4 fxg5 17. Rad1 Qf5 18. Rfe1 Bc5 19. Nd6+ Bxd6 20. Rxd6 Nf6 21. Rdxe6+ Kf8 22. Qxb4+ Kf7 23. Qc4 Kg6 24. g4 Qf3 25. R1e3 Qd1+ 26. Kg2 Rad8 27. Rxf6+ gxf6 28. Qe4+ Kf7 { The game is a draw. } 1/2-1/2
  • 2
    Channeling my inner Marc Esserman I suspect he would look at 8 or 9 Bd5 ... Whether it's any good I'll leave for better players to divine, at least while I am supposed to be working!
    – Ian Bush
    Commented Mar 24, 2020 at 16:19
  • It is surprisingly "sound", Lc0 rates it -0.5! after exd Nxd5, Stockfish thinks you've just blundered a piece. It performs very well in online chess.
    – B.Swan
    Commented Mar 24, 2020 at 16:27
  • After 8 Bd5 exd5 9 exd5 my Stockfish puts white better at ~+0.4 . But 8 ... Bb7 looks critical
    – Ian Bush
    Commented Mar 24, 2020 at 16:42
  • Yes, 8 Bd5 exd is not good for Black. I was talking about 9. Bd5 exd, where the capture is also pretty much forced, as the bishop attacks the rook.
    – B.Swan
    Commented Mar 24, 2020 at 16:44

2 Answers 2

[Event "Morra Gambit Accepted - Paulsen Formation"]
[FEN "RNBQKBNR/PPPPPPPP/8/8/8/8/pppppppp/rnbqkbnr b KQkq - 1"]
[StartPly "14"]

1.e4 c5 2.d4 cxd4 3.c3 dxc3 4.Nxc3 e6 5.Nf3 Nc6 6.Bc4 a6 7.O-O b5

To investigate the position after 7...b5, I setup a round-robin tournament between Stockfish NNUE 14.1, Stockfish Classical 14.1, Komodo Dragon 2.6.1, and Leela Chess Zero (Lc0) 28.2. These 4 engines are arguably the top chess-playing entities on the planet at the moment.

Each engine played W and B against every other engine. The time control was 10/10 and each engine was given 16 logical cores (3080 Ti for Lc0) with 8 GB of RAM.

Based on the results:

  • All 12 games were drawn. This is strong evidence for the theory that White has sufficient compensation for the pawn.
  • In every game every engine evaluation stayed between +1/-1 pawn. So no dramatic surprises, and more evidence that White has sufficient compensation.
  • Most games were fought with a material imbalance as part of complex unbalanced positions.
  • Most games were very tactical in nature - so fully fitting the typical Morra Gambit theme.
  • Every engine played 8. Bd3, not 8. Bb3.
  • Several games ended with a Black fortress - Black down material, but creating an impenetrable barrier to the White queen.
  • Several games included a White sac on b5.
  • As Black, Dragon always insisted on returning the pawn by allowing a4, axb5, and Bxb5.

To be honest, I see very little there, but Re1 also just looks like it is not in the spirit of the opening since it does little to add any pressure to the center. Of course, if black were to play d5, then it would make sense, but black will probably refrain from playing that for quite a while. Bc2 probably should be played there, and follow it up with the standard Qe2 and Rd1.

Overall, the only compensating factors right now are a slight lead in development, and more space; but as always, in such positions, if the other side is very solid, they can catch up in development, and then the extra pawn will become a major factor.

There is a reason the Morra is only popular at lower levels: It just loses a pawn, and there are not many redeeming factors.

  • The second two positions that you added are not really relevant to the main question. In the second, with the Be2, black would never play Na5. The third is more of a tactical slugfest, and is more about exact calculation. Commented Mar 24, 2020 at 15:50
  • Re1 is used to "secure" the knight on c3, as on Black's ...b4 the knight can jump into the center with Nd5! without being captured. It is also played by Esserman and is the choice of the engine aswell. I added the two other positions to show that White is indeed "forced" into this position if Black delays a6 and plays an immediate Na5.
    – B.Swan
    Commented Mar 24, 2020 at 15:51
  • @77and33is100 It was not the choice of my engine on a pretty strong computer, and I played the Morra up until I was about 1800, and switched to 1.d4, and it just does not seem to fit with the typical plans that I used to play. It is really SLOW, in my opinion as a fairly strong player, as long as black makes sure to play moves that will not benefit that move in the short run, and it is pretty easy to do. As soon as d6 is played, Nd5 becomes fairly unplayable there. Commented Mar 24, 2020 at 16:01
  • SF11 at depth 30 likes Re1 most, Lc0 likes Re1 (gives it as only move), it makes sense as a human to put the rook opposite the king, but that is not the point of discussion. I play as White.
    – B.Swan
    Commented Mar 24, 2020 at 16:15
  • It makes some sense to put the rook opposite the king, but only when there is a chance that the e-file will become open, and I just do not see that happening. In most Morra Gambits, it makes more sense to put it opposite the Qd8, and pressure the Pd7 since it is also hinders the Bb7 from developing in some cases. I let my Stockfish run longer, and it did start to like Re1 by a HAIR over Bc2, but in my opinion, if Re1 is the best move, then it is probably already time to look for a different line as a practical matter. It really does not fit, and give any real attacking chances. Chess is also Commented Mar 24, 2020 at 16:27

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