Aldi, Lidl and Waitrose see 'strong' Christmas sales
Discount and premium supermarket chains fared better than mid-range brands over the Christmas period, according to research firm Kantar Worldpanel.
Aldi, Lidl and Waitrose reported strong Christmas growth, Kantar said. Of the UK's "big four" supermarket chains, Sainsbury's outperformed its rivals.
Morrisons, which reported worse-than-expected festive trading last week, saw its sales and share of the market drop.
Researchers Kantar looked at spending for the 12 weeks to 5 January.
Edward Garner, director at Kantar Worldpanel, said: "Among the big four, only Sainsbury's was able to resist the relentless pressure from the discounters and Waitrose. Now catching up with Asda, it managed to hold share and out-perform the market with year-on-year growth of 3.1%".
The supermarket sector in the UK has for some time been regarded as being dominated by the big four: Tesco, Sainsbury's, Asda and Morrisons.
However, in recent years discount supermarkets such as Aldi and Lidl have seen their popularity surge, while at the other end of the market, Waitrose has also reported strong growth.
'Champagne and prosciutto'
In September last year, Aldi reported a 41% increase in annual revenue to £3.9bn. It also expanded the number of its stores by 34 in 2012 and 50 in 2013, expressing confidence in UK consumers' appetite for its goods.
Morrisons, the smallest of the big four by market share, has suffered from this increased competition at the value end of the market.
Like-for-like sales at Morrisons fell 5.6% in the six weeks to 5 January, the supermarket reported last week.
Kantar's Mr Garner said: "As revealed last week, Morrisons suffered the most among the major supermarkets with its share dropping from 12.0% last year to 11.5% now.
"The absence of an online offering is a major factor in its decline".
Mr Garner told the BBC that Aldi and Lidl are appealing increasingly to a wider range of shoppers as they diversify their offering - selling some luxury products "like champagne and prosciutto ham" as well as basic goods.
However, he added he did not think most UK consumers would start to do their entire shop in one of the discount chains "because their offering is too limited".
Kantar said Waitrose - at the more premium end of the supermarket sector - saw sales growth of 6.4% for the Christmas period compared with a year earlier, while Aldi was up 29.4% and Lidl 17.5%.
Tesco saw growth of just 0.2%, said Kantor, Asda's sales grew by 0.8%.