[#]72....b2Not losing, but72...Qh3+73.Kg5Qc3was simpler. White
can't make progress.73.Qe8+Kh774.Qe4+Kh8?74...Kg8!is much
better because of the following trick:75.Kg6[#]Qg7+!!76.hxg7b1=Q77.Qf5(77.Qxb1stalemate)Qe4!78.Kg5Qe3+79.Qf4Qe7+and Black
will draw.75.Kg6...Now to avoid mate Black has to give up the b-pawn. Then
it's still a draw (a handy ending to know), but in practice a nightmare for
Black to hold.75....b1=B76.Qxb1Qc6+77.Kg5Qc5+77...Qd5+78.Qf5(78.Kh4Qe5)Qd8+!!, since the obvious79.Qf6+only draws afterKh7!80.Kf5(80.Qxd8stalemate!)Qd3+and the
king won't escape Black's checks.78.Qf5Qe3+??Black was already playing
on the increment and it's practically impossible for a human to hold this
position, but it's theoretically drawn with perfect play. Here78...Qc7!still holds, since79.Qf8+Kh780.Qf6Qd8!!is again drawn.79.Qf4Qc5+80.Kg6and Black resigns, since either Qf4-b8 or Qf4-f6 follows.1-0