KEG: A fine comeback win for Maroczy. The commentary on this game in the Tournament Book, however, is little short of pathetic.
Maroczy played the Berlin Defense to Cohn's Ruy Lopez, and got much the worst of the opening. With his unfortunate 15...Bb4 (15...Rf8 was best), Marozcy was in trouble. Cohn's clever 16. Ne4 was a fine exchange sacrifice which Maroczy wisely declined (if 16...BxR 17. Bf5 would be powerful for White), but he was nonetheless probably lost after 17...Be7 (he might have tried 17...Qe8).
However, after achieving a won game through fine play, Cohn began seeing ghosts and playing tentatively. He engaged in a long misguided effort to win Maroczy's pawn at a7 with 18. Be3 (18. Qe3 or 18. BxB would both have maintained his edge). He followed this up another poor move (21. c4 instead of 21. Nc5) and the win was gone. Then, still operating under his delusion of winning Maroczy's a pawn, Cohn erred with 24. Qb2 (24. Nxd6 still left him with a slightly better game) allowing Maroczy to come to life with a brilliant exchange sacrifice (24...RxB). If anything, Maroczy--who picked up a Bishop plus a pawn and the attack for his sacrificed Rook--now had the somewhat better chances.
The Tournament Book concluded that Cohn's game was lost after Maroczy's exchange sacrifice. In fact, what remained was a very unbalanced position. Fritz gives Black only a slight edge, and I would venture to say that Magnus Carlsen would have won the position after 25...Rxf4 from either side.
But Cohn's remaining play was feeble. His 26. Qe2 was silly (26. h3 protecting the vulnerable g pawn was indicated), and after Maroczy missed the powerful 27...e5, Cohn gave White two connected passed pawns in the center with 28. cxd5 (28. Kh1 protecting the King was much better). Even then, Cohn probably was not lost.
The game essentially ended with Cohn's suicidal 29. Nd3. Although the Tournament Book has no problem with this move, it in fact hands Maroczy a lethal pin through Cohn's Rook. Fritz' evaluation of the position before 29. Nd3 was (-0.53). After this blunder (29. Rf1 being best) Fritz rates the game as (-7.22). In other words, this was the losing move in this game.
After his blunder on move 29, Cohn seemed hell-bent on creating a help-mate position. His remaining play is otherwise inexplicable, and his 34. RxB walked into a forced mate.
Maroczy's opening play in this game was not good, but with a few glitches, his play after move 15 was inspired. He defended well when Cohn had the edge, and his exchange sacrifice on move 24 was clearly the highlight of the game. While he missed 27...e5 (his 27...Qb6 gave Cohn equal chances), from then on he ruthlessly exploited every one of Cohn's mistakes.
This win moved Maroczy into a tie for first place in the tournament with Janowski (who drew this round with Showalter) at 4.5 points apiece in five games.