Solution
39… a3 40. ♝xg6 g2 41. ♝c2 g1=♛
The position
This expert puzzle (rating 2414) asks Black to move to find the winning idea. It features these themes: Promotion, Sacrifice.
It is Black to move. Look for the tactic hiding in the position — Promotion, Sacrifice. 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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