Cyber Monday could lose its crown as the U.K.'s biggest pre-Christmas online retail day, with "Middle Cyber Monday" taking its place.
Global research group Experian expects visits to U.K. retail websites to reach 113 million on Cyber Monday, the Monday after the U.S. Thanksgiving holiday at the end of November.
But Christmas shoppers are changing their habits, and Cyber Monday could soon be eclipsed by "Middle" Cyber Monday, a week later, Experian said.
The U.K leads Europe in online shopping - due in part to the popularity of online grocery shopping - followed by Germany and France.
(Read more: Online sales 'to hit £5 billion' this Christmas)
Shoppers increasingly expect retailers to be able to deliver gifts closer to Christmas, and are therefore more likely to shop on the second Monday of December, Experian's research found. The growing popularity of click-and-collect services, which grew 40 percent year-on-year in 2012, also means people are more likely to delay their online shopping for Christmas.
Previous research has shown that Monday is the most popular online shopping day, usually attracting 12 percent more visits than any other day of the week.
Mintel, the market research group says 17 percent of U.K. consumers will be using click-and-collect for present-buying this Christmas.
The market research firm expects U.K. online sales to grow by 16 percent year-on-year in December and adds that 34 percent of shoppers will do most of their present-shopping on the web.
James Murray, digital insights manager at Experian Marketing Services explains told CNBC this Christmas is going to be the biggest ever in terms of online retail visits and added that for the first time ever, the U.K. will reach the three billion mark for visits to retail websites during December 2013.
According to Murray, we're currently seeing a "homogenization of shopping days as consumers are less confined in their shopping habits". Therefore, "well-defined peaks and troughs of shopping activity over Christmas" are unlikely to be seen, due to the growth of mobile and "the ease of quick one-click shopping."
The group recommends that retailers tailor their campaigns to offer the best experience to customers both on the high street and on the go.
Both research groups also stressed the need for retailers to broaden their offering to mobile as this holiday "will be one of the first major mobile Christmases".
Richard Perks, director of retail research at Mintel said 8 percent of all shoppers were intending to use their smartphone or tablet to buy gifts.
"Looking further ahead", Perks said, "we think retailers need to cater to these mobile-enabled shoppers" by launching options for customers to check stock availability in nearby stores on the go.