Openings › Mate in one › November 2025 › Exercise 4 of 4
Mate in one: White to move (exercise m1-202a247c21)
White to move and mate in one. In this position White can give checkmate with one move. The position comes from a rated Lichess game of November 2025.
Last move: 27…Ng5 (Black's knight from e4 to g5); 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 bishop move.
Hint 2: which square?
The mating move goes to g3.
Show the solution
One move gives checkmate:
- Bg3# (f4 to g3). After this move, the white bishop on g3 gives check to the black king on h4, and Black has no legal move: checkmate. The black king on h4 has no safe square to go to (g3, g4, g5, h3 and h5). Its own knight on g5 stands in the way. h5 is covered by the white pawn on g4. The king may not take the white pawn on g4: the white pawn on h3 guards g4. The king may not take the white pawn on h3: the white king on h2 guards h3. The white bishop on g3 cannot be captured: the king may not take it, as the white pawn on f2 and the white king on h2 guard g3. The white bishop on g3 stands right next to the king, so nothing can be put in between.
Our code tried every legal move of White in this position: this is the only move that gives checkmate.
The position as text
- White to move.
- Last move: 27…Ng5.
- White: king h2; rooks d1, f1; bishop f4; knight d8; pawns a2, b2, c3, e3, f2, g4, h3.
- Black: king h4; bishop g7; knights f6, g5; pawns a7, b6, g6, h7.
- Castling: no longer allowed for either side.
- FEN:
3N4/p5bp/1p3np1/6n1/5BPk/2P1P2P/PP3P1K/3R1R2 w - - 5 28
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 November 2025. In that game White 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.