Black decides he can't mate after all. This move was widely denounced, but that's a bit unfair. [Indeed, Tartakower and du Mont claimed this move lost the game.] Black still has a winning position in the endgame. But a quiet alternative such as 24...Kb8 would serve much better.
After 26. Bd3!
Black may have been counting on winning the d-pawn after 26…Bf6 (or inflict 27. d5 Bxc3+ damage). But because 26…Nxd4? loses to 27. Bxd4 Rxd4 28. Bxf5+, White buys time for Nd2 and f3-f4!
White has gotten past about-to-lose – but he should still lose eventually. Trading bishops is still the smoothest win, e.g. 27…Rhe8! 28. Kf1 Na4 29. Rb1 Be3!.
After 31. Kf1
White signals that he has survived. This move says that he can just try to improve the placement of his pieces (Nd4-e6) and wait for Black to prove that he is winning.
Tarrasch didn’t respond well when confronted with unexpected obstacles. His best games were linear – an opening advantage grew logically and steadily until, by move 30 or 35, it had become overwhelming.
In this game his edge was growing until move 22 or so and seemed to be only a few good moves away from becoming unstoppable. But now he sees he’ll need more than a few good moves. He needs a pawn-break, eitehr from …b5 or …c6. And he sees that 31…c6 can be answered by 32. d6!, after which 32…Rxd6 33. c5 Rxd3 is dubious (34. Rdxd3 Nbd5 35. Bd4).
Nevertheless 31…Na4! and 32…c6 would get him closer to a win, e.g. 32. Nd4 c6 33. Ne6 Nb2.
Black insists. He would still have a serious edge after 32…Nb6 33. Nd4 Na4 or 32…Nd6 and …Ne4. For example, 32….Nb6 33. Nd4 Ne4 34. Bxe4 fxe4 35. Ne6 Rd7 36. Re3 Nf5! and then 37. Rxe4 h3 38. Kg1 Nd6.
Black loses this game because he is too concerned with keeping his material edge. The tide turns after 34…Kc7 35. Nd4 Bxd4 36. Bxd4 Rh7 37. Be5+ Kd8 38. Rb8, intending 39. d6 and wins. But Black could save himself wth the 36….cxd5! exchange sacrifice.
After 35. Nd4! Bxd4?!
White has an attack, but it can be handled by 35….Rd7 36. Nxc6 Nxc6 37. dxc6 Rc7.
A knight on b7 is always bad, Tarrasch might have said. It was widely believed that White still has a clear advantage after 38….Ne4 39. Bxe4 fxe4 40. Rhb3 followed by Rb8+ or Rb7.
But the simple 40…a5 holds because of 41. Rb7 cxd5 42. Bb8 Nf5! and then 43. Rxh7 Rxb8, when Black can again think about winning.
No better is 39. d6 because of 39…Nd2+ 40. Ke2 Nxb1 41. dxe7 Rxe7 42. Bxb1 g5.
After 40. Rc1
After his minor errors at moves 24,, 27, 34 and 35 and the major ones at moves 32 and 38, Black’s position has fallen into the can-lose category. Some observers felt it was much worse than that. Teichmann though Black was “hopelessly lost” three moves ago.
But this is the decisive error. It’s common sense, Lasker might say, that Black should use his badly placed knight (40…Na5!) rather than reposition the other one.
After 44. Rce1!
The rooks rule (44….Rd8 45. Re7!).
Black is also lost after 45. Nd8 46. Re8 Kb8 (47. Rxf8 Rxf8 48. Re8).>