KEG: The analysis of this fabulous game (featuring three exchange sacrifices) by keypusher is superb. I will therefore focus on those points on which keypusher has not spoken or concerning which we disagree.
keypusher has explained the ideas Lasker's 5...a6, but I prefer 5...cxd4 which leads to near equality and in many variations avoids the problems of the isolated Queen's pawn altogether. After Lasker's 5...a6, Janowski could have gotten the better game with either 6. Nf3 or 7. Rc1.
Janowski's 7. cxd5 was surely a mistake and the source of much of his later troubles. 7. Rc1 was best.
I agree with keypusher that Janowski's 15. Rd1 was questionable. The simple 15. h3 seems best.
After Janowski's 15. Rd1, Lasker's 15...Qe7 seems pointless. Why not just 15...0-0 at once! Once Lasker had played 15...Qe7, Janowski could have fought for the initiative with 16. e4.
Unlike keypusher, I like Janowski's 17. g4, which was the start of the excitement on the king's side. I see no better move for White.
But then Janowski went overboard. His 18. Bb1 was misguided. He should have cleaned up his messy king's-side with 18. Kg2. Lasker, in turn, would have done better with 18...Bc3 rather than his prosaic 18...Rfe8.
All of the above, however, was just the prelude to the battle that broke out with Janowski's 19. g5. keypusher has explained the flaws in this move. The Tournament Book's claim that White had no alternative is simply wrong. 19. Qd2 was best.
Lasker's 19...Bg7 was a slight inaccuracy. He should have posted his Bishop more agressively with 19...Bc3.
In any case, Janowski's 20. h4 was bad, and keypusher's statement that Janowski was in a "bad way" after this move is quite right. Janowski should have played 20. Kg2.
Lasker's 20...Bg4 was brilliant, and should have brought him victory, especially after Janowski's 21. Rxd5? Come what may, Janowski had to play 21. Kg2.
After Janowski's 21. Rxd5?, Lasker had a neat intermediate move: 21...Rcd8. There was no need to rush to win the exchange with 21...Nd4 (Lasker's move). Nonetheless, Lasker's move won the exchange for a pawn and was good enough for victory.
But Lasker, having outplayed Janowski and obtained a winning advantage, seemingly lost his bearings for a while. His 25...Bh8 was inferior to keypusher's 25...Be5. And Lasker's 26...Rc5 was inferior to 26...Red8.
Janowski should have brought his Rook into play immediately with 28. Rh1 rather than his 28. BxB. But despite these slight inaccuracies, Lasker's winning edge was still intact. But then he seemed to lose the thread of the game for a while (incredible for Lasker!).
Lasker's 32...Qc6 was not as accurate as 32...Re6, and his 34...Bc3 was doubtful (as keypusher has noted). 34...Qe6 seems better.
Lasker's 37...Red8 seems to have been an oversight for the reasons explained by keypusher. Lasker should have played 37...Qb5 or 37...Qd7. Now, the win was doubtful at best.
Lasker's advantage was gone entirely after what keypusher correctly calls a blunder: 39...Rd1.
Lasker could probably have stayed in the game with 40...R1xd4. His 40... Rg1+ was another blunder, and now Janowski could and should have won the game, as I will attempt to demonstrate in my next post on this game.