Shoppers are expected to spend a record £4.2bn on food and drink in the week before Christmas Day, despite a sluggish start to the festive trading period.
Nielsen is forecasting a late spending surge following a “slow start" to festive grocery shopping, which it blamed on mild weather in November and “the distraction of Black Friday”.
The bumper £4.2bn spending spree would represent a 3.6% uplift on the corresponding week last year, and 50% more than a typical week in the year.
However, a third of shoppers expect to spend less on festive groceries overall than they did last year.
Nielsen UK head of retailer insight Mike Watkins said: “With Christmas Day falling on a Monday, people are likely to delay their big Christmas shop until the final week and we expect nearly all shoppers will visit a grocery retailer at least twice that week.
“There’ll be a particular surge between Thursday 21 and Saturday 23 when over half of shoppers are likely to be shopping for the second time that week.”
Watkins noted that one in five shoppers will opt to shop on the Friday, allowing the weekend to be spent with friends and family.
“The seven days trading available up until the Sunday is good news for the supermarkets, which should benefit the big out-of-town stores in particular as shoppers take advantage of Christmas promotions and stock up on fresh foods,” he added.
Tesco on top
Among the big four, Tesco registered the most improved performance in the 12 weeks to December 2, Nielsen's data suggested, with sales up 3.4% year-on-year.
Sainsbury’s recorded a 1.9% uplift, while Asda and Morrisons grew sales at 1.7% and 1.6% respectively.
Lidl was the fastest-growing grocer according to Nielsen data, posting a sales spike of 16.5%, while discount rival Aldi's revenues advanced 13.2% during the period.
Outside of the discounters, Marks & Spencer had the best sales growth figures, up 4.6% year on year.
Rival data from Kantar Worldpanel also anointed Tesco as the fastest-growing member of the big four, with the market leader growing sales 2.5% in the 12 weeks December 3.
Sainsbury's sales advanced 2%, Asda grew at 1.2% and Morrisons posted a 1.4% uplift.
Kantar figures suggested Aldi was the fastest-growing grocer during the period, growing revenues 15.1% to take its market share to 6.9%.
Discount rival Lidl's sales jumped at the slightly slower rate of 14.5%, as the German duo continued to outpace the market.
According to Kantar, Ocado was the next fastest-growing grocery business, having enjoyed a 5.2% uplift during the period.
However, the online grocer's market share remained flat year-on-year at 1.3%.