The last-minute festive shopping rush is set to spill over into a record-breaking online Christmas Day splurge with 117 million visits to retail websites expected on December 25.
It comes as retailers make a final sales push to win trade from those who have left their spending to the very last minute, with a separate report suggesting 17.5 million would be hitting stores on Christmas Eve.
Data services company Experian predicts UK consumers will spend 45 million hours shopping online from December 24-26.
Visits to retail websites on Christmas Day itself are forecast to rise by 9%, with a 5% climb on Boxing Day to 118 million and Christmas Eve to see 22% more visits, rising to 105 million.
The analysis also forecasts that December is on course to see more than three billion visits to retail websites, the first time this has happened in a single month.
James Murray, digital insight manager at Experian marketing services, said Christmas 2013 online visits had consistently outperformed last year.
He added: "Shopping habits are changing, with Christmas Day becoming a significant shopping day during the period.
"As a result, we anticipate a more sustained shopping pattern during this period, moving away from the traditional peaks and troughs usually evident during holiday season."
Online retail giant Amazon has already predicted it will see record Christmas Day sales this year.
Its "Boxing Day" sales will begin a day early and transactions are expected to peak at around 8.30pm as customers log in after a day's festivities.
Meanwhile, figures from Sainsbury's Bank suggest 17.5 million have left some festive shopping to the last minute and would be doing some on Christmas Eve, with around 2.5 million leaving more than half of their Christmas spend until then.
Retailers are in the midst of a critical few days which for many represent a make-or-break chance to restore their fortunes at the end of a dismal 2013.
Department store John Lewis, which tracks weekly sales, has announced record takings of £164.4 million for the seven-day period ending on Saturday night.
But analysts fear that, across the retail sector, heavy discounting - including a 30% off promotion at embattled Marks & Spencer - will leave many businesses suffering a profits hangover in the new year.
Jon Edwards, commercial director at The Mall at Cribbs Causeway, near Bristol, said the shopping centre had been busy as shoppers were keen to snap up last-minute bargains.
"I'm happy to report that it's been a busy few weeks here at The Mall and we've welcomed thousands of shoppers through the doors," he said.
"Many of the centre's big names are trading well and it's great to see such a positive reaction to some of our newer stores including Superdry, Thomas Sabo, Lakeland and Bose.
"We expect the next two days to be some of the busiest of the year in the run-up to Christmas and with the Boxing Day sales just around the corner, no doubt it's going to be a positive start to 2014 as well."
London's shopping district suffered a 9% fall in footfall compared with last year over the week ending on Sunday, illustrating the challenge facing retailers.
The figures from the New West End Company, representing 600 retailers across Bond Street, Oxford Street and Regent Street, also showed visits to the area over the first three weeks of December reached 19.5 million - down 6.2% on last year.
Spokeswoman Sally Eden said retailers were responding for the need for value for money with "highly competitive promotions across the board".
She added that men shopping for last-minute gifts were expected to drive sales in the final couple of days before Christmas.
Department store Fenwicks said it had received a boost to designed lingerie and nightwear over the weekend as men showed photographs on their smartphones to sales staff to allow them find the right sizes.
Meanwhile, Superdrug said it expected to see the "last-minute man" phenomenon drive sales of 140,000 bottles of fragrance on Christmas Eve alone.