For traditional merchants such as Macy's, the day after Thanksgiving is a sacrosanct one--time to jump-start holiday sales by showcasing Santa, stretching store hours and offering big discounts.

But guess who's trying to rain on the day-after-Thanksgiving parade?

Internet retailers did their best yesterday to reroute Americans who consider their annual trek to the malls to be a holiday in itself. They blitzed the airwaves with ads, waved post-turkey-day deals and chased after shoppers heading to brick-and-mortar retailers.

But while busy consumers may applaud online merchants for making their lives simpler, many seemed shocked at the idea of surfing the Web on a day that has become a time of bonding for families and friends, as well as an opportunity to earn a shopping badge of honor.

"It's a big day for people to go out," said John Konarski of the International Council of Shopping Centers. "People have been in the house all day Thursday. They want to see what's out there. They want to get out of the house."

Undeterred, the e-tailers pounced on the public yesterday. Chief among the aggressors was Internet gateway Yahoo Inc., which went off-line to usher people online. People wearing sandwich boards advertising the benefits of Yahoo shopping--"no perfume attacks" and "no parking required," for instance--brazenly marched in front of Macy's, Nordstrom and other stores lining busy streets in Chicago, New York and San Francisco.

Yahoo, which features an online shopping mall, also offered free garage parking to thousands of customers headed to brick-and-mortar stores in all three cities. Those in San Francisco were steered toward the lobby of the Downtown Center Garage, where the Internet company had set up an interactive kiosk showing people how to shop online and send free Yahoo greeting cards.

"People love it," said Luanne Calvert, a "buzz" marketer for Yahoo's shopping division. "You don't even have to leave the garage."

She acknowledged, however, that shoppers did indeed take off for the stores, even those who tried the kiosk.

Internet gift shop RedEnvelope Inc. ran a shuttle for shoppers in retail districts in San Francisco, San Diego, Chicago and New York. Between stops, "spokesmodels" wearing black pants and red ski jackets suggested that shoppers consider buying gifts such as RedEnvelope's model sailboat and a shot-glass chess set.

"Some people revel in the shopping activity [at traditional stores], and some get frustrated," said Peter Aronson, marketing director for San Francisco-based RedEnvelope. "We want to minimize that frustration and point out the alternatives at the point where they're most receptive."

Even before the season, online shops such as Delias.com, a clothing store for teens, and apparel boutique Bananarepublic.com had been offering free shipping on many purchases, trying to remove one of the roadblocks to online purchasing. In recent weeks, e-tailers have become more aggressive about discounting.

Online music retailer 800.com says new shoppers at its World Wide Web site receive $20 off a purchase of $100 or more. Customers who created holiday wish lists yesterday at RedCart.com, an online shopping service, could get an item under $50 for free. And upstart iJewelry.com staged a "Thanks for Giving" after-Thanksgiving sale, giving customers who spent $100 or more a $50 discount on their next purchase.

"We're saying, 'Stay out of the crazy malls,' " said David Norman, executive vice president of merchandising for iJewelry.com, which is based in Troy, Mich.

But even with the boom in e-commerce, many shoppers seem to be ignoring the noise coming from cyberspace.

Brick-and-mortar stores, they said, still offer a better selection and bigger discounts on the ground, especially on the Friday after Thanksgiving. Shopping online may be enjoyable, but some customers said there's no substitute for the thrill of the holiday shopping frenzy.

"It's the atmosphere, the people and the music," said Brenda Compton, a Stanardsville, Va., resident who woke up at 2:30 a.m. to shop at stores that opened early at Leesburg Corner Premium Outlets. "It's shop till you drop. I don't think you can do that [online]."

"It's kind of like a social experience," said James Piotrowski, a Bristol, Tenn., resident who stopped at Fair Oaks Shopping Center in Fairfax County after visiting relatives in Northern Virginia. "It's nice to come out and see all the hustle and bustle."

At Fair Oaks, children waited in line yesterday to have their pictures taken with Saint Nick as shoppers hustled from one post-Thanksgiving sale to another.

Near Santa was one of his reindeer and an imposing moose. Children stared in wonder at a menagerie of giant stuffed animals, including a kangaroo, pandas and a towering giraffe with a chimpanzee clinging to its neck.

"We came strictly for the decorations," said Bruce Sydnor, 47, as his wife, Inge, took their 4-year-old daughter, Audrey, to visit Santa.

Sydnor, an Army colonel who lives in Woodbridge, said there was a time to shop in cyberspace--and a time to hit the stores.

"If I knew exactly what I had in mind, I would go online," he said. "But it takes a long time to go through Web sites. . . . The mall is a lot more fun. You bring your family. You have something to eat. You get to see the object you're buying instead of a poor picture of it."

The emerging marketplace online hasn't dimmed holiday sales forecasts for many brick-and-mortar retailers. With a robust economy and a strong stock market, analysts are calling for healthy retail sales.

A forecast by Deloitte & Touche and the National Retail Federation calls for sales of general merchandise, apparel and furnishings in November and December to increase as much as 6.5 percent from 1998, to $185 billion.

Online sales predictions vary, but most call for fast-paced growth. Jupiter Communications Inc.'s widely used projection is for Internet sales to double to $6 billion in the last two months of the year.

The explosion in sales has been fueled by customers like Chris Crooks, an information technology consultant from Alexandria who often shops the Web for books, software and other items.

He ventured off-line yesterday only because his wife had to work.

"I think we could get rid of all this," he mused afterward, staring at the stores at Potomac Yards shopping center in Alexandria.

Comments like those strike a common chord of fear in traditional retailers and shopping malls. Some have been trying to keep consumers by offering free Santa photos and introducing services such as valet parking, even as their own retail tenants are opening Web sites.

At least one mall has decided it doesn't want to share its space with the Internet. Last week, the Saint Louis Galleria in Missouri barred its 170 stores from promoting e-commerce inside the mall.

"We're looking at the future," said Shelly Schembre, the mall's marketing director. "And yes, anything that drives sales from the mall concerns us."

CAPTION: Max Shipp, 7, and his father, Thomas, search for Pokemon toys yesterday on a Yahoo Web site at a kiosk in a San Francisco FAO Schwarz.