48...Bd4+?
[48...axb6
preserves winning chances]
49.Kg2
Bxb6??
I never even considered the following switchback. I suspect that I was mentally tired after struggling with some 'flu-like virus for the last fortnight and coaching for 3 hours prior to this game. Either way, I was quite oblivious to any mating threats.
50.Bc8+
f5
51.Ba6
[51.Ba6
exf4
52.Be2+
f3+
53.Bxf3#
] 1-0