The supermarket price war is set to intensify after a study found discount store Lidl was almost a third cheaper than the major chains.
The German low cost business was included in The Grocer magazine's weekly price survey for the first time, which found that it sold a basket of common groceries for 29% cheaper than Tesco.
Lidl also scored 78 out of 100 for customer service at its High Wycombe store in Buckinghamshire, just one point behind the week's winner, the Tesco Extra in Streatham, South London.
It came level with Waitrose and beat Asda, Morrisons and Sainsbury's.
A weekly shop at Lidl cost £49.23, compared with £57.83 at Morrisons, £59.95 at Asda, £63.73 at Tesco, £64.50 at Sainsbury's and £71.84 at Waitrose.
Only three Lidl products could be found cheaper elsewhere - cauliflower at Asda and Chicago Town pizza and Laughing Cow cheese at Morrisons.
Both Lidl and fellow German discounter Aldi made record sales as price competition in the sector weighed heaviest on the country's big four players, according to figures released last month.
Lidl saw its sales leap 19.5%, which kept the firm's market share at its record level of 3.6%, Kantar Worldpanel reported.
Sales at Aldi rocketed 32% over the year taking its market share to a record 4.8%, just behind upmarket Waitrose.
This week Waitrose became the latest store to offer four pints of milk for £1, the same as Tesco, Sainsbury's and Asda and only slightly more than Lidl and Aldi who both charge 95p.
Meanwhile, figures released today show supermarket price wars continued to keep a lid on food and non-alcoholic beverages, which saw a third month in a row of flat or negative inflation - the longest period in nearly a decade.
The Grocer news editor Ronan Hegarty said: "It's not a huge surprise Lidl is cheaper but the interesting thing is they are ranking highly for customer service.
"The big chains now have to up their game.
"The days of Tesco having 30% plus of market share are long gone. There is too much competition."