The sandwich's status as the bread and butter ingredient of the British lunchbox is under threat, sales data shows.
The culinary creation that Britain gave the world 250 years ago is falling out of favour amid competition from continental alternatives, researchers said.
Sales of bread, traditional rolls and baps across all retailers have fallen by 1.2%, while sales of croissants have soared by 33% and tortilla sales have grown by 18%.
Bagels, the New York favourite, have increased by 11%, according to data from TNS Global Market Research.
Supermarket Tesco said the new sales data showed Britain was moving away from its "hackneyed continental image of a nation that lives on fried breakfasts, and a meat and two veg diet".
Andy Simpson, a spokesman from Tesco, said: "There are so many bread varieties from all around the world now available in the UK and these are drawing sales from traditional loaves, rolls and baps which have reigned supreme in bakeries for hundreds of years.
"While croissants have been commonplace across the UK since the 1980s, it's naan bread, chapattis, bagels and more recently tortillas that have now established themselves as popular snack alternatives to the traditional sandwich.
"The main reason for this is that the UK has become more multicultural and is now home to many different races and nationalities who have helped popularise different cuisines here.
"But the trend is also down to the sheer diversity of bread now available to shoppers such as varieties from Italy, Ireland, Germany, France and the Middle East, as well as those from France, India, Mexico and New York - all of which are now commonly found on supermarket shelves."