A survey released on Sunday by the National Retail Federation and Prosper Insights & Analytics estimates that some 122 million Americans will shop online on Cyber Monday. That’s up only slightly from last year’s 121 million shoppers.

But the increase is notable coming off the Thanksgiving-Black Friday weekend that saw 108.5 million people shop online, well above the 99.1 million who hit stores. What’s more, major retailers, notably Walmart (WMT) started their Cyber Monday sales way earlier than in preceding years, lest they cede a millimeter of the market to Amazon.com. (Walmart now refers to the shopping occasion as Cyber Week.)

In much the same way Black Friday, as an event, ended up being diluted by Thanksgiving store openings (that started in 2011) and deals starting earlier in November, Cyber Monday is losing some of its impact as a one-day event. In addition to Walmart and Amazon’s deals being spread out, Target is offering discounts on Sunday as well, not only online but, more crucially, in stores. That move, which reflects how people shop in the year 2016, is also meant to lower stress on Target’s web page, which last year buckled under the intense e-commerce pressures that come hand in hand with Cyber Monday.

The evidence of the migration of shopping to e-commerce is incontrovertible: Adobe told Fortune on Sunday that e-commerce sales between Thanksgiving and Saturday rose 17.3% to top $7.2 billion.

Within e-commerce, a key shift is continuing: some 28 million of those shoppers plan to shop Cyber Monday deals from their phones, continuing a trend that explains why the likes of Walmart, J.C. Penney (JCP)and Kohl’s (KSS) have invested heavily in their mobile shopping apps.

“The brick-and-mortar retailers have made a big leap with their online efforts this year,” Moody’s analyst Charlie O’Shea told Fortune this weekend.”They’re really getting it.” And they need to: as Fortune reported on Friday, Amazon has said it is featuring 75,000 deals during the week of Cyber Monday.

Walmart says 60% of Black Friday sales event orders placed on Walmart.com came from mobile devices, something the company says shows customers are growing more comfortable with pushing the “buy” button on smartphones. That retailer has been trying to hook people away from Amazon onto its shopping and mobile payment apps. Walmart has a lot riding on Cyber Monday: It recently finished an overhaul of its marketplace business, something that has allowed it to nearly triple its product assortment in the last year (and offer many items it would never offer in store, like Michael Kors (KORS) handbags).

Of course, all stores have been stress testing their websites to make sure they can withstand what will be an extraordinary amount of traffic on Monday. That’s for good reason—the security firm Upguard recently estimated that just ten minutes of downtime could translate to a loss of over $2 million in sales.