7…c6In positions of this kind it is preferable to guard the Pawn by B - K 3; the square Q B 3 should be reserved for the Knight. White, of course, has no intention of exchanging his B at Kt 2; but Black wishes to compel him to do so; therefore the Kt at Q 4 and B at K 3 are well posted.
20.Qa3If 20) R x R ch, R x R; 21) Q x R P, B x P, White would have a slight weakness in his Q R P, but he might have opposed the Rook on the K file and probably escaped with a draw.
21.Bxh3His position is weak, but this exchange does not help him, but only develops Black's Queen to a strong square. He ought to play B - Q B 3.
22.Bc3The right move was 22) R - B 2. Black might then have continued 22) .... R x R ch; 23) B x R, R - K sq; 24) Q x R P, B x P; 25) Q - Q 2, Q - K 3; 26) R - B sq, Q x R P, or 25) B - B 3?, B x B, followed by R - K 7.
Emanuel Lasker, The International Chess Congress, St. Petersburg, 1909 (1910) · Public domain · source