Find the decisive blow (difficulty 1595)

12345678 hgfedcba

Black to move

Show solution
12345678 hgfedcba
  1. g3–f5 key move
  2. e4–f5
  3. c6–f3
  4. g2–f3
  5. b8–e5
  6. d3–d4
  7. e5–d6
  8. f4–e2

What makes it

A 3-point sacrifice — the forcing line does the rest. No check, no capture: just a quiet move, and the defence caves in. The forced line runs 8 plies.