Marshall–Capablanca, from their 1909 match in the United States. The young Capablanca — who would go on to win the match overwhelmingly — here loses with the Queen's Gambit Declined and annotates his own defeat with characteristic candour. His original notes from Chess Fundamentals (1921), now in the public domain, are reproduced below.

1. 5…Ne4 I had played this defence twice before in the match with good results, and although I lost this game I still played it until the very last game, when I changed my tactics. The reason was my total lack of knowledge of the different variations in this opening, coupled with the fact that I knew that Dr. E. Lasker had been successful with it against Marshall himself in 1907. The object is to exchange a couple of pieces and at the same time to bring about a position full of possibilities and with promising chances of success once the end-game stage is reached. On general principles it should be wrong, because the same Knight is moved three times in the opening, although it involves the exchange of two pieces.
2. 7.Bd3 P x P is preferable for reasons that we shall soon see.
3. 8…Nd7 Now P x P would be a better way to develop the game. The idea is that after 8...P x P; 9 B x B P, P - Q Kt 3, followed by B - Kt 2, would give Black's Bishop a powerful range.
4. 9…O-O No longer would 9...P x P; 10 B x P, P - Q Kt 3 be good, because 11 B - Kt 5 would prevent B - Kt 2 on account of Kt - K 5.
5. 12…c5 Played with the intention of obtaining the majority of Pawns on the Queen's side. Yet it is doubtful whether this move is good, since it leaves Black's Queen's-side Pawns disrupted in a way. The safer course would have been to play P - B 3.
6. 13…b6 This exposes Black to further attack by P - R 5 without any compensation for it. If I had to play this position nowadays I would simply play 13...R - K 1. Then after 14 Q x P, Q x Q would follow, and I believe that Black would regain the Pawn. If, instead, White played 14 P x P then B - Kt 5 would give Black an excellent game.
7. 16…Nd7 Black's position was bad and perhaps lost in any case, but the text move makes matters worse. As a matter of fact I never saw White's reply B - B 5. It never even passed through my mind that this was threatened. Black's best move would have been 16...K R - Kt 1.
8. 17…Rfc8 From bad to worse. Kt - B 3 offered the only hope.
9. 21…Rab8 The game was lost. One move was as good as another.
10. 25.Qxb6 Of course, if 25 Kt x B, R - Kt 8 ch would have drawn. The text move is pretty and finishes quickly. A well-played game on Marshall's part.