That would take e-commerce’s share of total holiday season sales past the 10% mark for the first time, a major new milestone for online retailers. Last holiday season, more shoppers went online than to stores over Thanksgiving weekend, which is the kickoff to the busiest shopping period of the year.

And just like last year, Amazon.com (AMZN) is expected to be a major factor behind that growth after accounting for one quarter of total online sales in November and December.

“It should be even higher this year, as Amazon’s revenue growth continues to outpace e-commerce growth as a whole,” said eMarketer retail analyst Yory Wurmser.

To counter that, eMarketer advises, traditional retailers need to make sure their fulfillment centers are prepared to help physical stores deliver orders.

That emphasis is already apparent: while retailers like Target (TGT), Kohl’s (KSS) and Macy’s (M) are hiring roughly the same amount of seasonal workers this Christmas period, overall more of those jobs are going to support e-commerce facilities like distribution centers.

What’s more, many retailers are tapping their huge networks of stores to speed up delivery and better compete with Amazon. For instance, Target will use 1,000 of its 1,800 stores to help fill online orders, more than double the number last year.

Overall, analysts expect a better holiday season this year: Deloitte, a consulting firm, expects sales to grow 3.6% to 4%, while AlixPartners sees them ticking up between 3.3% and 4%. Still, it’s easy to see why brick-and-mortar retailers are scrambling to prepare for online shoppers: if eMarketer proves to be right, those growth figures would only be one-fifth of e-commerce’s 17.2% clip.