Kasparov wins a tempo by walking his king around a triangle so that the white king must leave the squares that stop the f-pawn.
From Alburt–Kasparov (USSR Championship 1978). Black has pawns on f3 and h4 against White's h3; the kings are on e4 and f1, Black to move. White's king wants to sit on f1/f2/g1, guarding f2 and g2 and keeping the f-pawn from queening. If the white king could stay on f1 and f2 forever, Black would make no progress; so Black must create a position in which White, to move, has to leave his post.