U.S. shoppers who missed out on deals this past Black Friday are expected to flock to online sites Cyber Monday, testing the limits for some retailers that have been investing heavily on their e-commerce operations to stay relevant in a brutal space.

Retailers across the country are fighting to entice people to come to their websites, offering new services such as deliveries with no minimum order limits and an assortment of deals.

Amazon.com Inc and Target Corp are pushing free shipping with no purchase minimum for the first time this holiday season.

Cyber Monday is expected to draw over 75 million shoppers, according to research firm Planalytics. The much-hyped marketing day is expected to be the largest U.S. online shopping day in history, yielding $7.8 billion in sales or 17.6 percent growth over last year, according to Adobe Analytics, which tracks transactions at most of the top U.S. online retailers.

But retailers will also face a deluge of online orders, which will task their e-commerce sites. If not backed with the right IT infrastructure the lure will lead to headaches—forcing outages and other technical glitches due to heavy traffic.

Read more in Reuters.