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Openings › Mate in one › September 2026 › Exercise 2 of 5

Mate in one: White to move (exercise m1-5ede2c3564)

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 September 2026.

Last move: 47…Ka4 (Black's king from a3 to a4); its two squares are marked on the board.

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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 queen move.

Hint 2: which square?

A mating move goes to a1, a2 or b4.

Show the solution

Three moves give checkmate:

  1. Qa1# (b2 to a1). After this move, the white queen on a1 gives check to the black king on a4, and Black has no legal move: checkmate. The black king on a4 has no safe square to go to (a3, a5, b3, b4 and b5). a3 is covered by the white queen on a1. a5 is covered by the white queen on a1. b3 is covered by the white king on c3. b4 is covered by the white king on c3. b5 is covered by the white pawn on c4. No black piece can capture the white queen on a1. No black piece can move to a2 or a3 to block the check.
  2. Qa2# (b2 to a2). After this move, the white queen on a2 gives check to the black king on a4, and Black has no legal move: checkmate. The black king on a4 has no safe square to go to (a3, a5, b3, b4 and b5). a3 is covered by the white queen on a2. a5 is covered by the white queen on a2. b3 is covered by the white queen on a2 and the white king on c3. b4 is covered by the white king on c3. b5 is covered by the white pawn on c4. No black piece can capture the white queen on a2. No black piece can move to a3 to block the check.
  3. Qb4# (b2 to b4). After this move, the white queen on b4 gives check to the black king on a4, and Black has no legal move: checkmate. The black king on a4 has no safe square to go to (a3, a5, b3, b4 and b5). a3 is covered by the white queen on b4. a5 is covered by the white queen on b4. b3 is covered by the white queen on b4 and the white king on c3. b5 is covered by the white queen on b4 and the white pawn on c4. The white queen on b4 cannot be captured: the king may not take it, as the white king on c3 guards b4. The white queen on b4 stands right next to the king, so nothing can be put in between.

Our code tried every legal move of White in this position: these are the only moves that give checkmate.

The position as text

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 September 2026. From a game that began with the Scandinavian Defense: Mieses-Kotroc Variation. 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.