High street retailers are preparing for what they hope will be the biggest day of the year amid gloomy sales figures in the last dash to Christmas.
This weekend will be "the big one" as consumers spend up to £5 billion, the British Retail Consortium predicts, with today being the busier of the two days - primarily because of longer opening hours.
Visa Europe also expects today to be the year's busiest shopping day, with customers set to spend £1.26 billion on their Visa cards alone.
The company predicts it will process 31.9 million transactions today, with 2pm to 3pm expected to be the busiest hour.
It said shoppers appeared to be saving up for a "spree" this weekend, with figures showing an incremental
increase in spending in recent weeks.
Visa Europe commercial director Dr Steve Perry said: "The way in which Christmas falls this year means that, in comparison to 2011, we appear to be a week behind in terms of consumer spending.
"This is borne out in the Visa Weekly Christmas Spend Tracker which shows that UK consumer spending is down -2.9% annually.
"It appears that shoppers are holding off their spending sprees until the weekend when we anticipate that Saturday will be the busiest shopping day of the year, with consumers set to spend £1.26 billion on their Visa cards alone.
"Competition for consumer spending is fierce, with growing numbers of consumers still visiting online retailers to snap up bargains ahead of anticipated discounting on the high street in the final furlong before Christmas."
A spokeswoman for John Lewis said the last two weekends had been record-breakers in terms of sales and momentum was continuing to build, adding that "another record-breaker isn't out of the question".
And Waitrose is expecting today to be the busiest food shopping day of the year.
But the Local Government Association (LGA) said confidence on the high street remained low as Britain prepared for "what is traditionally the busiest shopping weekend of the year".
Its annual Christmas survey found that 84% of town centre managers said confidence among shoppers had either not improved or worsened compared with this time last year.
The LGA suggested that the particularly cold and wet start to the winter could also be taking its toll on the number of shoppers visiting town centres.
The LGA's chairman of its economy and transport board said: "Last year, 86% of those who took part in our survey thought there would be no improvement in consumer confidence on the high street in 2012 and it would seem from today's results that they were right on the money.
"Worryingly, the outlook for next year is not much brighter.
"People's shopping habits are changing, and we need new creative approaches to revitalising our town centres."
Tim Walley, general manager at Birmingham's Bullring shopping centre, said: "Today we expect to welcome in the region of 220,000 visitors to Bullring as they take advantage of the final weekend before Christmas.
"This Christmas we essentially have an extra weekend of trading in comparison to December 2011, so we're expecting a bumper weekend.
"Tomorrow we expect another 120,000 customers will visit the centre."
At the Westfield Derby shopping centre, Richard Thornton marketing and communications manager said plenty of shoppers had arrived and were ready for the centre to open at 9am, today.
"It is extremely busy, much busier than it usually is for this time on a weekend and the car parks were extremely busy when I was coming in this morning," he said.
"We're open from 9am until 7pm, and we had about 50 people queuing outside the Pandora jewellery store before it opened this morning."
At the Touchwood Shopping Centre in Solihull near Birmingham, managers were expecting up to 30,000 people through their doors today.
Some 275,000 shoppers are expected to descend on Bluewater in Kent this weekend.
More than 600,000 visitors have flocked to the shopping centre - which extended its opening hours until 11pm - over the past five days.
Robert Goodman, Bluewater's general manager, said: "With this weekend being the last chance for many people to complete their Christmas shopping, we are expecting Bluewater to be very busy."
Jo Tallack, general manager at the Highcross Leicester shopping centre, said: "With one full weekend left before Christmas, we're expecting both Saturday and Sunday to be exceptionally busy at Highcross.
"Last weekend we saw almost 170,000 people through the doors, which was our busiest weekend in three years and our busiest Sunday since we launched in 2008. We're expecting this weekend to be just as busy - if not more so - than last weekend.
"Total year-to-date sales are up by 5% at Highcross, with like-for-like sales up 3% - we're confident this will be another successful Christmas at the centre."
Glasgow`s Braehead shopping centre said Saturday was expected to be its busiest day of the year, with huge crowds also anticipated for Sunday.
General manager, Peter Beagley said shoppers were queuing outside stores before they opened at 9am.
He said: "We opened all the doors at the mall entrances earlier than we would normally do and that meant shoppers could queue inside the centre out of the rain.
"By 10am our car parks were full and we had staff on duty directing cars to spaces when they became available.
"Despite the economic climate people are going out to enjoy their festive season this year and to make sure no one is missed out on the Christmas present list."
A spokesman at Sheffield's Meadowhall shopping centre predicted that 120,000 to 130,000 shoppers will pass through the doors today.
"Meadowhall, as expected, is busy," a spokesman said. "It's not mayhem but it is very busy."
She said major stores such as M&S were enjoying particularly strong sales.
Dave Bradley, a manager at the White Rose Centre in Leeds, said: "It's very busy here on the run-up to Christmas and a couple of Sundays ago we had the best Sunday in our 15-year history.
"We've got extended opening hours, which is helping, and today our 5,000 parking spaces are getting full, which gives you an idea how busy we are.
"Sales are across the board. The White Rose is a big place for clothing, which is selling very well."
Ryan Manson, general manager for Union Square shopping centre in Aberdeen, said: "We have already seen a busy start to the weekend, with shoppers out in force to pick up their must-have last minute gifts.
"We also saw queues form outside of stores, including Zara, Pandora and O2, as well as our car parks, early this morning.
"This follows a bumper week for the centre after welcoming over 253,000 shoppers across the last five days, an 11.5% increase on last week.
"Footfall for Friday alone was up 12.1% on last Friday, demonstrating the growing momentum amongst shoppers as Christmas approaches."