UdayanOwen: What a beautiful game, a model for white isolated d-pawn strategy.The question has been posed about what would happen if 23...Bxd5 or Nxd5. There is actually an embarrassment of tactical riches for white in this position and both moves fail rather dramatically:
23...Bxd5 24.Nxf6 Bxf6 25.Bxd5, when the piece can't be recaptured (25...exd5 26.Rxe8+ Qxe8 27.Qxf6, when immediate mate on g7 can't be avoided without catastrophic material loss, eg., 27...Qe5 28.Qxe5 f6
). An alternative win in this line after 25...exd5 is the more spectacular 25.Qxf6!, since if 25...Rxe1+ 26.Rxe1 Qxf6 27.Re8#).
So 23...Bxd5 leads to a forced loss, what about 23...Nxd5? The correct move is 24.Bxd5, and now there are two options for recapture:
24...exd5 25.Nf6+ Bxf6 26.Rxe8 (or 26.Qxf6! wins again) Qxe8 27.Qxf6
; if after 25.Nf6+, black tries 25...Kh8, then 26.Nxe8 wins a whole rook, since if 26...Qxe8 white has 27.Qf6+! Bxf6 28.Rxe8#.
After 23.Nxd5 24.Bxd5, the other recapture is 24...Bxd5, but now white has the pretty 25.Rxd5!
If 25...Qxd5, now 26.Nf6+ Bxf6 (or else lose the queen) 27.Qxf6 with the winning mate threat on g7. White also has 27.Qxd5, when the queen can't be recaptured because of back rank mate.
In the line 23.Nxd5 24.Bxd5 Bxd5 25.Rxd5!, if black tries 25...exd5 then white plays 26.Nf6+, when 26...Bxf6 loses to the familiar idea of 27.Rxe8 Qxe8 28.Qxf6
(but this time not 27.Qxf6?? Rxe1+ 28.Kh2 Qxf6
).
In the previous line after 26.Nf6, if black instead tries 26...Kh8, then simply 27.Nxe8 when the knight is again immune (27...Qxe8 28.Qf6+! Bxf6 29.Rxe8#). Hence, white is a piece ahead, and furthermore, black can't stop both threats 28.Nxc7 and 28.Qxf7. Game over.