Openings › Mate in one › December 2025 › Exercise 2 of 4
Mate in one: Black to move (exercise m1-fbb1d74736)
Black to move and mate in one. In this position Black can give checkmate with one move. The position comes from a rated Lichess game of December 2025.
Last move: 33.c4 (White's pawn from c2 to c4); its two squares are marked on the board.
Pick a piece, then its square. Keyboard: Tab to the board, arrow keys to move, Enter or Space to pick.
Hint 1: which piece?
Look for a pawn move: the pawn becomes a new piece.
Hint 2: which square?
Every mating move goes to f1.
Show the solution
Two moves give checkmate:
- f1=Q# (f2 to f1). The pawn becomes a queen on f1. After this move, the black queen on f1 gives check to the white king on h1, and White has no legal move: checkmate. The white king on h1 has no safe square to go to (g1, g2 and h2). Its own rook on g2 and pawn on h2 stand in the way. g1 is covered by the black queen on f1. No white piece can capture the black queen on f1. The check cannot be blocked on g1: the white rook on g2 is pinned to its king by the black queen on c6.
- f1=R# (f2 to f1). The pawn becomes a rook on f1. After this move, the black rook on f1 gives check to the white king on h1, and White has no legal move: checkmate. The white king on h1 has no safe square to go to (g1, g2 and h2). Its own rook on g2 and pawn on h2 stand in the way. g1 is covered by the black rook on f1. No white piece can capture the black rook on f1. The check cannot be blocked on g1: the white rook on g2 is pinned to its king by the black queen on c6.
Our code tried every legal move of Black in this position: these are the only moves that give checkmate.
The position as text
- Black to move.
- Last move: 33.c4.
- White: king h1; rook g2; knight h4; pawns a2, c4, h2.
- Black: king d7; queen c6; rook g8; bishop b5; pawns b4, c5, e6, f2, h7.
- Castling: no longer allowed for either side.
- En passant: a pawn may capture on c3.
- FEN:
6r1/3k3p/2q1p3/1bp5/1pP4N/8/P4pRP/7K b - c3 0 33
Where this exercise comes from
The position comes from a rated game in our sample of the Lichess open database (CC0 1.0), from the monthly file of December 2025. From a game that began with the Queen's Pawn Game: Modern Defense. In that game Black gave checkmate with the next move. We show no player names and no link to the game. Our code tried every legal move of the position and lists every move that gives checkmate; the list, the hints and the explanations are checked again each time the site is built. How the exercises are chosen: Mate in one and How it works.