Black To Play And Draw

FROM this morning's second round of the 23rd 4NCL U2000/175.

Black to make his 33rd move in Spanton (1927/168) - Rob Tokeley (1840/148)

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33...cxb4!
Everything else loses, eg 33...axb4 34.dxc5+ bxc5 35.cxb4 cxb4 36.Nxb4, and the passed pawn will win. Also no good is trying to keep the position closed with 33...c4, eg 34.Nb2 axb4 35.cxb4! In this line, 34...Be6 is met by 35.f5 Bd5 36.b5 Kc7 37.Kf4, eg 37...Kd6 38.Nd1 Bf3 39.Nf2 Ke7 40.Ne4 Bd1 41.d5 Ba4 42.d6+ Kxd7 43.Nxf6+ Kxd6 44.Nxh5 etc. This last line is not all forced, but Black loses because 33...c4 creates a serious weakness.
34.cxb4
Not 34.axb4?? a4.
34...Bxd3 35.Kxd3 axb4 36.axb4
The ending is drawn because White's king cannot get into Black's position.
36...Kd5 37.b5
White loses after 37.f5?? b5.
37...f5 38.Kc3 Kd6 39.Kc4 Ke6 40.d5+ Kd6 41.Kd4 f6 42.Kc4 Kd7 ½–½