1.e4 Probably a wise change in opening move, and subsequent variation, from that which occurred in their 1929 encounter and also from the 1.c4 move played in some of the intervening games. In that time scale Botvinnik had grown enormously in strength and won quite a few strong events. He had in 1933 also drawn a match with the Czech player Flohr then generally regarded as one the strongest players in the World.
1...e5 2.Nc3 Nf6 3.f4 The Vienna Gambit similar in some respects to the Kings Gambit except White has developed his queen's knight early.
3...d5 [3...exf4 is not recommended as after 4.e5 the knight must be "undeveloped" by 4...Ng8 when White has an advantage in space and development. (similarly after 4...Qe7 5.Qe2 Ng8 ). Curiously though the 2300+ elo rated correspondence player Wochnik has won quickly as Black from the former position on a couple of occasions.) ]
4.fxe5 [4.exd5 e4 transposes to a Kings Gambit.; whilst 4.d3 is a line favoured by the Old Masters such as Blackburne, Zukertort, Steinitz, and Tchigorin.]
4...Nxe4 5.Nf3 Nc6 [Black has several bishop move options here such 5...Be7 or; 5...Bg4 ; and also 5...Bc5 The latter preferred in the game Donnelly-Bowyer, Ward-Higgs 2003 inducing 6.d4 when after 6...Bb4 7.Bd2 c5 8.Bd3 Nxd2 9.Qxd2 Nc6 10.Qf4 cxd4 11.Nxd4 Qe7 12.Nxc6 bxc6 Black, a CCIM and former British CC Champion, had achived in what seems the easiest way a comfortable game without any real risk.]
6.Qe2?! Whilst not an outright blunder this is not the best as the queen goes "wandering" on the queens-side without generating meaningful threats. Instead [6.Bb5 as played a long time ago in Steintiz-Kockelhorn/Wemmers, Collogne Consultation Game, 1881 and more recently in, for instance, Hector-Caruana, Malmo 2012, keeps the game balanced.]
6...Bf5 7.Qb5 [Neither does 7.d3 help White much as after 7...Nxc3 8.bxc3 d4 Black retains the advantage as in Philippe-Bacrot, Corsica Masters Rapidplay 2012.]
7...Nc5 This is good but an even stronger move, played in more recent games, is [7...a6 demonstrating the disadvantage of the early queen sortie. Play may continue 8.Qxd5 (8.Qxb7 is no better 8...Nb4 9.Nxd5 Ra7 (even stronger than the natural move 9...Qxd5 ; and avoiding the capture 9...Nxd5 which loses to 10.Qc6+ ) 10.Qxa7 Nxc2+ 11.Ke2 Qxd5-+ Katz-Stoicescu, USA-ch 19 sf, ICCF E-mail 2010.) 8...Nb4 9.Qxd8+ Rxd8 and Black was already close to winning in Berg-Spassky, Bundesliga 1987.; Less clear are 7...Nxc3 8.dxc3 (8.Qxb7 Nb4=/+ Kusmierek-Gisy, Niedersachsen-ch U12 2006, and Peterson-Manne, Bergen op 2005. (but far stronger is 8...Nd4 9.Nxd4 Qh4+-+ ) ) 8...Qd7= Angelov-Todorov, Primorsko op 2016.; and also 7...Bc5 8.Nxe4!?=/+ (since definitely bad are 8.Qxb7 Nb4-+ Yano-Villalba, Florianopolis op 2017, and Perez Mijans-Espinosa Veloz, CUB-ch op Santa Clara 2007.; and 8.d3 a6 9.Qxb7 Na5-+ Fernadez Lopez-Getz, Andorra op 2012.) ]
8.d4 a6 [8...Bd3 is a tactical trick that doesn't quite work. For example 9.Bxd3 a6 10.Qxc5 Bxc5 11.dxc5 and White has 3 pieces for the queen and a more promising game.]
9.Qe2 So the queen has to ignominiously retreat and Black still controls e4. [9.Bg5 is no improvement as after 9...Qd7 10.Qe2 Ne4 Nilsen-O'Toole, Gibralter Challengers- A 2015, Black still keeps the advantage.]
9...Ne4 Occupying the key central square that Black controls which may be viewed as a strategic continuation in Botvinnik's style. However, Kan comes up with an inventive idea that introduced complex tactical possibilities into the game. [Recent games show that a stronger option is available to Black in 9...Nb4 10.Bg5 (10.dxc5 Nxc2+ 11.Kd1 d4 12.Bg5 Be7-+ Fierrro Baquero-Vajda, W-ch U-20 Girls Medellin 1996.) 10...Qd7 11.0-0-0? Na4-+ Cruz-Calcado, Sao Paulo op 2014.; Not quite as strong is the other possible knight move 9...Ne6 10.Be3 Nb4-/+ Pedersen-Pinter, World Student Team Ch, Teesside 1974 (10...Bb4= Gossip-Blackburne, New York Grand Tm 1889.) ]
10.Qe3 Nxc3 Botvinnik was a point ahead of the field at the start of this round with 10 points to Flohr on 9, Lasker and Levenfish on 8, and with Capablanca on only 7.5 points at this stage. With Flohr and Capablanca meeting in this round (a game which ended in the possibly expected draw) Botvinnik may have been motivated to play for a win in grabbing what turns out to be a risky pawn. The stigma of bad loses against Kan in the past may also have been a contributory factor in trying to win in this manner. The straightforward development move [10...Be7 would produce a less complex and balanced game.]
11.bxc3 Bxc2 12.Qf2 Gaining time so converting the pawn loss to, in effect, a reasonable gambit. [12.Ng5 is a decent alternative when play may go 12...Bg6 13.Be2 (but not immediately 13.e6 due to the calm reply 13...f6 ) 13...Be7 14.e6 and an unclear positions results.]
12...Bf5 13.Nh4 Be6 Safeguarding f7 and d5 and adding control over the c4 square. However, White remains with an easier game and can develop faster than Black.
14.Bd3 Qd7 15.0-0 Na5 16.Nf5 0-0-0 17.Qe2 [17.Rb1 immediately occupying the b-file is another reasonable plan.]
17...Qc6 18.Rb1 h6 19.Bd2 Nc4 Black has secured his king's position and stabilised the queens-side too.
20.Ne3 Nxe3 In exchanging off the strongly placed knight Black starts to go astray possibly with his 21st move in mind. [Again developmen with 20...Be7 seems called for if only to connect the rooks.]
21.Bxe3 Qxc3? A fatal error. Black grabs a second pawn and hopes to defend his king but opens a second file for White's rooks. [21...Be7 was now essential.]
22.Rfc1 Qa5 [22...Qa3 is of little hope since after 23.Rb3 Qa4 24.Qb2 the b7 pawn cannot be defended and advancing it opens the king up even more.]
23.Qc2 c6 Engineering a way for the queen to drop back and try and hold the king-side together. [23...Rd7 is no use as again b7 is too weak after 24.Qb2 ]
24.Bd2 Qc7 Black looks to have everything covered by in fact the a6 pawn is the fatal weakness in Blacks defensive wall, since the Bd3 can open the way for the White major pieces by a sacrifice.
25.Qa4 This wins comfortably as does the immediate sacrifice [25.Bxa6 bxa6 26.Ba5 Qd7 27.Qb3+- ]
25...Rd7 [25...Kb8 leaves the c6 pawn pinned so White crashes through with 26.Rxc6 ]
26.Bxa6 [Following 26.Bxa6 White wins easily after 26...bxa6 27.Qxa6+ Kd8 28.Ba5 (or 28.Rxc6 Qa7 29.Qc8+ Ke7 30.Bb4+ So another drastic loss for Botvinnik against Kan! However, with great strength of character Botvinnik went on to finish equal first in this very strong event, together with Flohr on 13 points, above former World Champions Lasker and Capablanca on 12.5 and 12 points respectively. Kan ended up not too badly placed on 10.5 points in equal 6th with Levenfish.) ] 1-0