Solution
51. a8=♛ ♜xa8 52. ♜xa8 f1=♛ 53. ♜a1+ ♚f2 54. ♜xf1+ ♚xf1 55. ♚d5
The position
This expert puzzle (rating 2354) asks White to move to find the winning idea. It features these themes: Skewer, Promotion.
It is White to move. Look for the tactic hiding in the position — Skewer, Promotion. Drag a piece on the board to play your move; the puzzle will tell you if you found the best continuation.
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