Deceptive Tactic

It took me a few minutes to solve this tactic from "Chess Tactics for Beginners":



The reason is that this looks like it's set up to be the old "windmill" or "see-saw" tactic: rook moves along a rank or file to deliver a discovered check; king moves; rook returns to original square to check. This is normally combined with other threats, such as merely gobbling material with the rook. I was thinking, "well, this is a tactics problem, the answer must involve this tactic" and kept trying to make it work.

Here, rook moves along the 7th rank or the g-file don't accomplish anything. I briefly wondered if the trick was to set up a winning zugzwang after moving the rook, but (for example) 1.Ra7+ Kg8 2.Bg7 can be met by 2...Rf7=.

Then I realized that a safe king move would also put black in zugzwang. Correct is 1.Ka2! Only the black rook can move, and it will be lost to the discovered check (e.g. 1...Ra8+ 2.Ra7+).

However, 1.Kb1 doesn't work, because here the white rook can't block the check after 1...Rf1+, e.g. 2.Ka2 Rf8.

The hardest part of this problem was letting go of my preconception of what the solution must involve, and postponing the "obvious" windmill pattern for one move. Sometimes familiarity with standard tactical motifs can blind you to other tactical possibilities.