|Pawn and Two: The opening and early middlegame were not a success for Rubinstein.|
At move 23, Tartakower had the advantage:
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Instead of 23...Qh4? 24.exf4 Nxf4+, and a near equal position, Black could have kept the pressure on with 23...fxg3!.
A possible continuation could be: (-.90) (26 ply) 23...fxg3! 24.hxg3 Nd8 25.Rd5 Nc6 26.e4 Ne5 27.f4 Nxc4 28.Qe2 Nxd2 29.Rxd2, (-.92) (26 ply) 29...h5 30.Qc4+ Rf7, (-.89) (26 ply) 31.Rd3 h4 32.Qd5 Qe6 33.Qxe6 Rxe6.
A few moves later, Tartakower could have maintained the balance with: (.00) (26 ply) 27...Qxc4 28.Re7 Qxa2+ 29.Rd2 Qc4 30.Rxd6 Rxd6 31.Qxd6 Qa2+ 32.Kh3 Rxf3 33.Qd7.
Instead, he slipped a bit with: (.42) (26 ply) 27...h4 28.Re4, and then followed with a huge blunder: 28...Rxg3+?? 29.hxg3 Qxg3+, (5.17) (24 ply), 30.Kf1 h3 31.Qe2.
At that point, Rubinstein had a clearly winning position.
Tartakower's blunder may have been due to time trouble, as the first time control was 2 hours for 30 moves.
It is more difficult to guess the cause of Rubinstein's blunder, 35.Qg3??.
After 32...Qh4 33.Qh2, Rubinstein may have trained his sights on the h-pawn, expecting 33...Rh6 34.Re8+ Kf7 35.Ree3 Qg4 36.Rxh3, with a clearly winning position.
Tartakower's reply 33...Qh7?, was not the strongest move, and may have been unexpected by Rubinstein. Fritz strongly prefers the following continuation: 34.Re8+ Rf8 35.Rxf8+ Kxf8 37.Qxh3, and White is clearly winning.
Rubinstein's 34.Rde3 was also strong and winning. Fritz indicates the following as the best continuation: 34.Rde3 Rf8 35.Qxh3 Qxh3+ 36.Rxh3, and White is winning.
Faced with a near certain loss, Tartakower dodges one more time with 34...Rh6. All moves by Black are losing, Fritz indicating this move was Black's 19th best choice, leading to a forced mate, after 35.Re8+ Kf7 36.R3e7+ Kf6 37.Qe2 Qb1+ 38.Kf2.
Even if White does not play the mating line with 35.Re8+, Fritz indicates Black can hang on for only a few more moves.
Perhaps this series of what may have been unexpected moves by Tartakower upset Rubinstein's calculations, causing him to be more likely to blunder, or to drift into time trouble, and then blunder. What followed, 35.Qg3??, dropping a rook, was a tragic oversight.
At move 37, Tartakower needed to exercise a little care, and not play 37...Kf7??, when after 38.Re7+ Kxe7 39.Qxg7+, Rubinstein would have won!