Achilles' heel

"We discovered an Achilles heel of antibiotic resistant bacteria," said Süel, a member of the Department of Molecular Biology at UC San Diego.

It's the Achilles heel of authoritarians throughout time.

Trump will be taking office having inherited an American economy that has performed very well, despite the discontent voiced among many voters who may have been the Achilles’ heel of Vice President Kamala Harris’ candidacy.

The fighting mentality has been Napoli’s Achilles heel for several years.

Before Singapore, you might have said that street circuits were Red Bull's Achilles heel, which would have led one to believe Las Vegas might be an issue for Verstappen.