Puzzle zu1z1_F — ELO 1039
This is a Black-to-move puzzle rated 1039 ELO. The first move is f6f5, tagged with 10 interpretable concepts and Lichess themes: advancedPawn, crushing, endgame.
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Position
Black to move. ELO 1039. Themes: advancedPawn, crushing, endgame, master, pawnEndgame, promotion, veryLong.
FEN: 8/8/5k1p/3KP2P/5p2/8/8/8 b - - 0 54
Show solution (10 ply)
Try to find the move yourself first — look for the rarest concept firing on this position before peeking. Solution sequence: f6f5 e5e6 f5f6 d5d6 f4f3 e6e7 f6f7 d6d7 f3f2 e7e8q
Concepts that fire on this position
Our SAE pipeline tagged this position with 10 active features. Each links to a page documenting that pattern in detail.
Why this puzzle is hard
The rarest pattern firing here is Pawn endgame with kings centrally placed and passed pawns on both flanks…, which appears in only 50 of our 9,950 puzzles (0.50%). Rare patterns tend to be the bottleneck — players who haven't internalised them will fail this puzzle even when their tactical calculation is otherwise solid.
The puzzle's Lichess ELO of 1039 reflects this: solvers below that rating typically miss the cue entirely.
Similar puzzles
Puzzles sharing the most concept tags with this one — a stronger signal than theme overlap because it reflects the actual patterns Leela recognises.
Train this pattern
Click through to the Climbchess trainer to attempt the position interactively against the same Leela network that tagged it. The trainer adapts difficulty using your live concept-recognition profile — it surfaces puzzles tagged with concepts you've been missing, not random brawls.
If you want the underlying methodology, the how-it-works page walks through the SAE training run, the labelling pipeline, and the puzzle-tagging procedure end-to-end.
Frequently asked
What is the rating of this puzzle?
1039 Lichess ELO. Solvers below that rating typically miss the key cue.
Which side moves first?
Black to move; the first move of the solution is f6f5.
What concepts does it train?
10 SAE-derived patterns including Detects kings in near-opposition or close proximity in…; Advanced pawn endgame with promotion threats, typically…; King actively navigating in an endgame where passed pawns….
Can I attempt it without an account?
Yes — Climbchess requires no signup or email. Click the trainer link to play the position interactively.