By Ben Klayman

DETROIT (Reuters) - Nike Inc may not be a World Cup sponsor, but the athletic clothing and shoe giant is the top brand online for consumers tuned into the world's biggest soccer tournament.

Photo: www.nike.com

Almost one-third of the online buzz around the World Cup in the month running up to the soccer tournament was focused on Nike, twice as high as rival and official sponsor Adidas AG, according to a Nielsen Co study. The World Cup kicked off on Friday 11 June in South Africa.

Nike was mentioned in 30.2 percent of the English-language messages online tracked by Nielsen from May 7 to June 6, making it the most talked about company in relation to the World Cup. Adidas AG was second at 14.4 percent.

"Social media has made ambush marketing easier, simply because of the virality of it," said Alex Burmaster, vice president of communications for Nielsen. "Some people call it an echo chamber."

Nielsen studied English-language World Cup related messages on blogs, message boards, groups, videos and image sites, including Flickr, YouTube, Facebook and Twitter.

It studied 10 World Cup sponsors with global footprints, as well as 20 of their rivals that are not sponsors.

Ambush marketing is when a company not affiliated with an event like the World Cup or the Olympics runs an ad campaign that links the advertiser to that event in the consumer's mind without saying the company is a sponsor.

Organizations like FIFA, which runs the World Cup, and the International Olympic Committee spend a lot of time and money seeking to stop ambush marketing as they derive billions of dollars from their sponsors. The World Cup will generate $1.6 billion in sponsorship revenue during the 2007 to 2010 quadrennium, according to IEG, a unit of advertising firm WPP Plc that tracks such spending.

In Nike's case, it created an ad dubbed "Write the Future," which includes such well-known soccer players as Wayne Rooney and Cristiano Ronaldo along with other stars like cartoon character Homer Simpson and basketball's Kobe Bryant. It has been viewed on YouTube more than 14 million times since mid-May.

Nine of the 32 World Cup soccer teams will wear Nike kits, including the United States, compared to 12 for Adidas.

Adidas produced its own Star Wars-themed World Cup video, featuring British soccer star David Beckham, that's drawn almost 2.8 million viewers since its release last week.

CARLSBERG PUSHES PAST BUD

Another successful ambush marketer was Carlsberg, which ran a star-studded "Legends" soccer ad, leading it to be mentioned 3.9 percent of the time, Nielsen said. That ranked the Danish brewer No. 6 on the list. World Cup sponsor Anheuser-Busch InBev's Budweiser did not make the top 10.

Burmaster said the Nike and Carlsberg ads were compelling, and backed by big marketing budgets that helped them catch on.

"Ultimately, no one's going to talk about something that isn't particularly compelling," he said. "Nike and Carlsberg, who aren't affiliated, have done very big, very public campaigns around the World Cup, and they have put them ahead of their competitors who are affiliated."

Not every sponsor came up short against rivals. Coca-Cola Co ranked No. 3 (11.8 percent) with almost five times the mentions of PepsiCo Inc, and Visa Inc at No. 5 (7.3 percent) had 15 times the tournament-related mentions as MasterCard Inc, Nielsen said.

Sony Corp at No. 4 (11.7 percent) was mentioned 7 times more than Panasonic Corp and 10 times more than Philips Electronics, Nielsen said.

(Reporting by Ben Klayman; Editing by Michele Gershberg and Tim Dobbyn)