KEG: Annother triumph for Lasker's psychology.
On the face of it, and contrary to what others have said on this site, Lasker's handling of the White side of this Ruy Lopez was--at least on a theoretical basis--very weak. His 17. Bc1, 18. Kh1, 19. Ng1, 20. f3, 21. Nf5, and 22. Nh3 were all condemned by Fritz, and appear to be more like one of Steinitz' hedgehog openings than the typically precise play of Lasker. Lasker didn't get around to playing the thematic c4 until move 23.
But Lasker knew his opponent, and it is obvious that Tchigorin was uncomfortable in this game in which he had traded off one of his beloved Knights and had to attack through pawn play on the Queen's side. Had someone like Karpov had Tchigorin's position, he would have put it to Lasker with, for example, 20...a4 (instead of Tchigorin's 20...b4), 21...bxc3 (instead of Tchigorin's 21...Qe6), 22...a4 (instead of Tchigorin's 22...Bc6), and 23...d4 (instead of Tchigorin's 23...dxe4).
Here's an interesting statistic, Fritz condemns six consecutive moves by Lasker (moves 17 through 22), but from move 23 through the end of the game, Lasker with one exception (Move 36) plays EXACTLY the moves suggested by Fritz.
As I said, Lasker knew his opponent. Once he got the edge in the game, there was no more psychology, and Lasker--literally--played like a computer. And Tchigorin, in a position in which he had to play tight defense, fell apart.
I agree that Tchigorin's 36...Bd7 was an oversight for the reasons identified by the Tournament Book and by keypusher. Indeed, Lasker's one and only mistake from move 23 through move 49 was his 36. Qe3 (36. Qa5 was much better). This move gave Tchigorin an opportunity, and he should have played 36...Qf7. But even with this move, Lasker would have had a significant edge, Tchigorin would have been on the defensive, and my money would have been on Lasker to win.
One clue to Lasker's strength is that 26 of his last 27 moves (over 96 percent) were the very same moves Fritz would have played.