NEW YORK (AP) — The Big Game is more than a week away, but Super Bowl advertisers are already out in force online, playing up celebrity cameos to drive buzz for their brands.

First-time advertiser Amazon on Wednesday teased its ad with Alec Baldwin. On Thursday, Hyundai revealed that Kevin Hart and Ryan Reynolds will be in ads showcasing Genesis and Elantra sedans. Skittles will have Aerosmith front man Steven Tyler promote the candy. Bud Light is creating its own fake political party with actors Amy Schumer and Seth Rogen. BMW’s Mini is cramming six celebrities into its ad (if not into its car). Even 1980s actor Scott Baio will make an appearance to promote avocados from Mexico.

Pre-game buzz is crucial; ads will cost as much as an estimated $5 million for a 30-second spot, up from $4.4 million last year. The cost, and risk, is worth it to the advertisers battling it out for the more than 114 million pairs of eyeballs the Big Game is expected to draw on Feb. 7. The Carolina Panthers will face off against the Denver Broncos in Levi’s Stadium in Santa Clara, California.

Pre-game teasers, which debut online one or two weeks before the game, can help advertisers stretch that investment over weeks instead of seeing it gone in 60 seconds. (Or even 30.)

“If an advertiser can get people thinking about the brand before the game, the risk goes down and returns go up,” says Tim Calkins, a Northwestern University marketing professor. “A celebrity is a great hook.”

Companies also appreciate celebrities’ reach on social media, which can help boost online buzz.

“Celebrities like Kevin Hart are adding thousands of followers a day,” said Dean Evans, Hyundai’s chief marketing officer. “We never know how much organic shares or unearned media (media mentions that aren’t paid for) we’re going to get from that kind of celebrity and social reach that that celebrity might have.”

There are, of course, downsides. A star can sometimes eclipse the brand, or worse, drag it down if people react negatively to a particular celebrity. Last year, T-Mobile’s Kim Kardashian ad was a dud on social media, said Devra Prywes, vice president of marketing for research firm Unruly, which monitors Super Bowl ads’ online buzz. The famous-for-being-famous celebrity just provoked too much Internet hate to be effective.

“No matter how carefully you choose a celebrity, they’re polarizing,” said Peter Daboll, chief executive of Ace Metrix, a firm that rates the effectiveness of ads. “Not everybody loves Justin Bieber.”

When there’s a good fit between celebrity and a brand, though, the payoff can be huge. Daboll pointed to popular ads by Snickers, which in the past have featured Betty White tossing around a football and character actor Danny Trejo playing a hungry Marcia Brady, an ad that landed in Ace Metrix’ list of top 25 Super Bowl ads of the past five years. Snickers has teased a spot this year featuring Willem Dafoe playing Marilyn Monroe.

Bud Light is hoping something similar happens with its ad showcasing actor/comedians Amy Schumer and Seth Rogen. They focused on regular-Joe Bud Light fans in last year’s Super Bowl ad, but this year, they went with celebrities to introduce Bud Light’s new packaging and logo.

“They’re current and relevant, so they were the perfect spokespeople to bring us back to the brand’s humor,” said Bud Light vice president Alexander Lambrecht.