6…Bxc3+The immediate capture appears to be best, as otherwise White can avoid the doubled Pawn by 7) Q - Q 2.
9…Bb7To 9) .... Q - K 5 ch the reply would be 10) K - Q 2, and White would then bring his Rooks rapidly into play.
10…Qh5White threatened Kt - R 4. But 10) .... Q - Q R 4 would at the very least have gained one “tempo” for the development.
12…Rc8He does not risk to Castle Q R, for fear White should attack by 13) P - Q R 4, P - Q R 4; 14) P - Q B 4 and later on Q R - Kt sq and P - Q B 5, but he underrates his chances of counter attack, which he might then have initiated by P - K 4. Hence Castles Q R would have been the right move, because Black would have then been able to advance in the centre and parry White's attack on the Queen's wing.
16…O-OBlack sees too late, that he dare not capture the Q B P. White would, in this case, first of all reply 17) Q - R 3 (17 .... Q - R 4; 18) Q - Q 6) and continue the attack by Q R - Q B sq and Kt - K 3. He would then easily regain the Pawn. In the nature of things, Black should not have opened the centre until his Rooks were available; for this reason P x P was a mistake.
22.g4A glorious attack. White prevents Black from freeing his game by P - K B 4 and Kt - B 3 and prepares K - R sq, and R - K Kt sq.
22…Qxh4Black fails to calculate accurately. He ought to defend himself by 22) .... K - R sq; 23) P - Kt 5, R - K Kt sq; 24) K - R sq, Q - B sq.
24.Nxe6Black had expected 24) Q x P ch and intended to play his King to K 2, where he would really have been quite secure.
25…Kh8If 25) .... K - B sq, White wins by playing 26. Q - Q 6 ch, and if 25) .... K - Kt 2, then Q - K 7 ch.
Emanuel Lasker, The International Chess Congress, St. Petersburg, 1909 (1910) · Public domain · source