Tesco, Britain's biggest supermarket group, outperformed its major rivals in the key Christmas period, achieving its highest grocery market share since January 2018, industry data showed on Wednesday.
Market researcher Kantar said Tesco's grocery sales over the 12 weeks to 26 December fell by 0.9% versus the same period in 2020, when several areas in Britain faced COVID-19 restrictions that boosted food sales.
On a two-year basis, Tesco's sales were up 10.1%.
Its UK grocery market share rose 0.6 percentage points to 27.9%.
Rivals Sainsbury's, Asda and Morrisons saw their sales fall by 4.4%, 3.9% and 6.5% respectively over the 12-week period compared with 2020.
Tesco's increasing dominance reflects the unmatched scale of its store and online operations, the success of its "Clubcard Prices" loyalty scheme and its ability to withstand supply chain disruption.
In October, Tesco raised its full year earnings forecast.
Some analysts believe it may raise its outlook again when it updates on trading on 13 January.
Its shares have increased 24% over the last year.
Kantar said total UK grocery sales were £31.7 billion ($42.9 billion) over the 12 week period, down 3% versus 2020 but up 8% versus 2019.
"The data suggests that while there weren't formal (COVID-19) rules in place across the UK this year, many people celebrated at home again due to Omicron," said Fraser McKevitt, Kantar's head of retail and consumer insight.
He noted that premium own-label sales broke records this Christmas with shoppers spending £627 million pounds on supermarkets' own upmarket lines over the four weeks to 26 December, an increase of 6.8% versus 2020.
Kantar said grocery price inflation reached 3.5% in December, its highest level since spring 2020, adding nearly £15 to shoppers' average monthly grocery bills.
It said prices were rising fastest in markets such as fresh beef, savoury snacks and skincare, while falling in fresh bacon, bath and shower products and spirits.
Last month, the Bank of England revised up its inflation forecast to predict consumer price inflation would peak at a 30-year high of around 6% in April.