Black Friday could become the UK's first £1 billion online shopping day as consumers and retailers prepare for the annual bargain frenzy.
Online retailers are braced for a shopper onslaught from midnight as deals go live, while some stores will open their doors at the same time to customers hoping to snatch bargains on everything from TVs to slippers.
Police have warned shops to ensure they have carefully thought-out security plans in place for the sales following chaos at a number of stores across the UK last year when huge crowds grappled for cut-price televisions and other big-ticket items.
Deputy chief constable Sue Fish, of the National Police Chiefs' Council Business and Retail Crime unit, has warned sales should be appropriately staffed and said police are not a substitute for instore security.
Experian-IMRG believes internet spending on Black Friday will hit £1.07 billion, a 32% increase on last year's £810 million - the first time that online retail sales in the UK will surpass £1 billion in one day.
The Centre for Retail Research expects a slightly more modest £966 million online, but predicts total Black Friday sales including at bricks and mortar stores will reach £1.39 billion, with shopping over the entire weekend culminating with Cyber Monday to hit £3.49 billion.
Visa Europe predicts that shoppers will spend £721 million online on its cards on Friday, up from £616 million last year.
Stores have been sending out teaser deals all week, but they are set to announce their biggest savings today, claiming customers can save anything from £10 on a DVD boxset to hundreds of pounds off large kitchen appliances and home technology.
But while stores prepare their websites and distribution centres for unprecedented demand, consumer advocates warned that shoppers should exercise caution amid the rush for bargains.
Martin Lewis, founder of MoneySavingExpert.com, has warned that the majority of Black Friday deals "aren't special" and advised shoppers to cross-check deals with items they actually need.
He said: "Above all, remember, if you don't want something, don't need it or can't afford it, then don't buy it."
And Which? urged shoppers to be prepared by registering for alerts from favourite retailers, searching for regular prices ahead of time in order to spot genuine bargains and to be aware that many deals are already available online.
It also warned that many websites slowed to a crawl last year, and suggested consumers register for online accounts early to "get in and out as quickly as possible".
Which? editor Richard Headland said: "There will be a whole host of deals available on Black Friday but not all of them will be genuine."
Those avoiding the event should find the nation's roads slightly quieter as people stay at home to shop online, according to analysis by Co-operative Insurance.
Figures for the past two years since Black Friday gained momentum in the UK show there has been a 5% reduction in the number of accidents, collisions and thefts on the day itself.
Nick Ansley, head of motor insurance at the Co-operative, said: "Whilst cyber traffic increases, our research suggests that many Black Friday bargain hunters are staying at home and doing their shopping online rather than taking to the roads and braving busy shopping centres."