Black Friday's round-the-clock sales apparently were just a warm-up for the homestretch of the holiday season, as many retailers will open their doors this weekend and keep them open straight through Christmas Eve.

In an unusually short shopping season and with just five days till Christmas, retailers are pulling out all the stops.

"It's crunchtime, " said Jamie Gutfreund, chief strategy officer at The Intelligence Group, a business research firm.

For the first time, Kohl's will stay open 108 hours starting at 6 a.m. Friday as "an added convenience to shoppers," said spokeswoman Jackie Kacala. Some Macy's stores will log 107 hours of nonstop sales before closing at 6 p.m. Christmas Eve.

And Toys R Us, which has helped pioneer extended holiday hours by shifting Black Friday sales to Thanksgiving, will offer 87 consecutive hours of shopping, opening Saturday at 6 a.m. and staying open until 9 p.m. Christmas Eve. The retailer's flagship store in New York's Times Square has been open since 8 a.m. Dec. 1 and will stay open for 566 hours -- the store's longest stretch of uninterrupted shopping.

"It's been an escalating progression," Gutfreund said. "Ten years ago it would have been, 'Oh, my god,' but now it seems to be not such a leap. ... It's all about the consumer now."

The shopping all-nighters started on Thanksgiving, when more stores than ever before opened to lure shoppers away from the dinner table and into the malls for sales that used to start on Black Friday. Retailers hope the extended hours will make up for the six days they lost this season; Thanksgiving fell late this year, leaving just 26 days until Christmas and setting up for the shortest holiday shopping season since 2002.

Many retailers depend on the holidays for up to 40 percent of their annual sales, and chopping almost a week out of the season could cost retailers about $1.5 billion in sales, according to a study by Adobe Digital Index.

"These final days are really important to the retailer," said Vera Gibbons a financial analyst and spokeswoman for Capital One. "This is it. This is make it or break it."

It's not just the marathon hours that will feel like round two of Black Friday -- retailers will also dangle sales and promotions in front of consumers, many of them as good as or better than Black Friday deals. Toys R Us is offering 50 percent off and buy-one-get-one deals, with a two-day sale starting Friday. Kohl's is offering cash back on purchases and Target has discounts of up to 60 percent, and has extended its in-store pickup service for online orders to 2 p.m. Dec. 24.

Experts expect consumers will hit stores at every hour of the day and night until Christmas. While retailers have struggled with the shorter season, so, too, have shoppers struggled to find the time to buy gifts.

"The next (week) will be extremely hectic and busy, and you'll see a huge ramp-up," said Michael Niemira, chief economist and director of research at the International Council of Shopping Centers.

According to a survey by American Express on Dec. 6-8, about 21 percent of consumers hadn't started their holiday shopping yet, and almost a quarter were only halfway finished.

Retailers' marathon hours
Stores open around the clock:
Macy's
Locations: Union Square in San Francisco and Westfield Valley Fair in Santa Clara. Other stores are open until 2 a.m. until Christmas Eve.
Hours: 7 a.m. Friday to 6 p.m. Tuesday
Toys R Us
Locations: Most stores except for Toys R Us Outlet and Express stores. Toys R Us has more than 20 locations in the Bay Area.
Hours: 6 a.m. Saturday to 9 p.m. Tuesday
Kohl's
Locations: Dozens of stores throughout the Bay Area
House: 6 a.m. Friday to 6 p.m. Tuesday
Stores with extended shopping hours:
Target: 8 a.m. to 11 p.m. though Monday, except closing at 10 p.m. Sunday. On Tuesday, 7 a.m. to 9 p.m. or 10 p.m., varying by location
Kmart: 6 a.m. to midnight through Monday, and 6 a.m. to 10 p.m. Tuesday
Nordstrom: Varies by store, but many open 8 a.m. to 10 or 11 p.m. through Monday, and 8 a.m. to 6 p.m. Tuesday