Sometimes it’s good for our chess psychology to be reminded that even our heroes are human beings, and make some pretty awful chess mistakes. I have collected some of these under the title “Homer Nods” (“And yet I also become annoyed whenever the great Homer nods off” Horace, Ars Poetica).
Here is a good one.
White has just played Kc7-d8, threatening mate, and Black, a recent World Championship Candidate, resigned.
I’ll bet it will only take you a minute to see what he should have done instead. If you do, you can say that at least this once you were sharper than the Grandmaster!