Last week’s puzzle came from an online training game against one of my pupils. (Well, he’s just about my only pupil at the moment!)

I was Black and decided it would be instructive to play 17… Nxg4 here.

The game continued 18. hxg4 Qxg4+ 19. Kh1 Bh5, which I’d thought in advance was winning, but I’d missed the move he found: 20. Nh2, after which the position was about equal. Black has rook and two pawns against bishop and knight.

What we both overlooked was that 17… Nxg4? is refuted by 18. Nh4!, when White’s threatening Nxg6 as well as capturing on g4.

“There’s a hole in my tactic!” – as there so often is.