Some supermarket own-brand champagnes are as good or better than some of the more well-known names, according to food critic Egon Ronay.
More than £300m is spent annually on champagne in the UK
He hailed as "excellent" three bottles of supermarket bubbly priced between £14 and £18 a bottle.
The judgement on the drinks - one from Marks and Spencer and two from Sainsbury's - comes as UK supermarkets grab a bigger slice of the market.
They took 64% of all sales in the year to October, from 59% a year ago.
After trying 30 different types of supermarket champagne, Mr Ronay said that the range and quality was "a revelation".
"It would certainly be a mistake to buy the well-known brands just because of the name on the label when some of the supermarket champagnes stand up to them very well," he said.
His favourites were M&S Champagne de St Gall Premier Cru Brut, Sainsbury's Vintage 1999 Blanc de Blancs Brut and Sainsbury's Blanc de Noirs Brut.
"Those which were in the first three are as good or better than some of the best," Mr Ronay said.
"Psychologically, because they are lower in price, people may think they are not as good - which would be a mistake.
"It is a wonderful thing that some of these excellent champagnes cost so little."
According to research firm AC Nielsen, UK customers spent £301.64m on champagne from shops, supermarkets and off-licences over the past year.
Of that amount, £192.73m was spent in the major supermarkets and the likes of M&S and Lidl.