X SESC Caioba Open · 2026.07.01 · Elo 2582/2476 · interesting · ★★★★
The daily position for Friday 21 August 2026. It is still open to solve — the grader reads your whole line, sidelines and evaluation included, before anything here is shown. Cover the solution and solve it first →
Black to move. the model gives this to 1 in 3 at this level.
The solution
41…♖︎ed8!(not41…♖︎e1?42.♔︎f3♔︎f843.h4♖︎h144.f5=)42.♖︎xd8+(42.♖︎a5is as good:42…♖︎xd343.cxd3c2−+)42…♖︎xd843.♗︎e4f544.♔︎f3♖︎d245.♔︎e3fxe4−+
41…♖︎ed8 — most players miss this
42…♖︎xd8 — the standard move
43…f5 — hard to find · worth +1
44…♖︎d2 — almost nobody finds this · worth +1 · the fair stop: the line may end here
45…fxe4 — routine — shown for completeness, never demanded
“hard to find”, “the natural move” and the rest describe how often this move is played by Maia-2, weighted across the 1500/1900/2000 audience the difficulty model is fitted on — a model of human play, not a count of anyone who solved this position.
Members can take this away as a PGN — the diagram, the verified line and their own analysis in one file, for a database, Anki or Chessable.
What happened at the board
Suleymenov found it · 0-1
the game ended inside the printed line — full game ↗
The field
81% of the 16 committed lines here found the key move — the model predicted 30% at this level.