"News-jacking" – piggy-backing on a trend or breaking news item to promote a message – is now seen as a crucial way to gain publicity. This weekend it also becomes a sport.

More than 100 teams drawn from communications companies, artists and advertising consultancies – including Google, M&C Saatchi and a New Yorker cartoonist – are to go head to head in a worldwide race to see who can spread their message furthest.

The Urgent Genius Weekender competition has been launched by iris worldwide, a creative consultancy. Its social media expert, Jon Burkhart, said that competition entries could include pictures, photographs, graphics, games or films, but must be "seeded" on the internet by 7pm tomorrow.

"We want to create crack units of real-time content-makers who supplement ad campaigns with ideas that help brands find their own voice in hot-topic conversations," said Burkhart.

Preparation for the race began on Friday when seven rival British teams met for a briefing on a secret "topic of global interest" at 6pm. Teams taking part in other countries were also briefed remotely and then, at 7pm, all the competitors – drawn from companies such as Google, Firecracker Films (producer of My Big Fat Gypsy Wedding) and advertising agencies BBH and DDB – were challenged to come up with the winning content.

In order to go on to win the race, entrants now have to generate more internet traffic than anyone else. The amount of interest online will be measured by the judges in terms of the number of "likes, shares and views" each entrant can attract in the seven days following the competition's launch.

The work that is judged to be the best will be showcased later in the year and then displayed in a book celebrating the competition. The results of the Urgent Genius contest will be adjusted using a formula developed to take into account each competitor's established networks, in an attempt to allow individual "lone rangers" to compete on a level playing field.

The importance of "news-jacking" is growing in the advertising industry in an age when the end of conventional advertising on television and in newspapers is widely predicted. The shift to online news products and the move away from scheduled television viewing both make it much harder for advertisers to reach the right audience. Yet media experts have also been forced to admit that, as technology changes fast, new ways of reaching potential customers or clients are easy to miss.

Simple "product placement", or even "going viral", are no longer enough. Advertisers need to understand the way to boost interest in a corporate message or in a political campaign by attaching it to something that already has a topical following.

"News-jacking" can be called many things, from "issue-jumping" to "trend-tagging", but it always involves publicists responding at speed to a window of opportunity. Recent examples of images or ideas that have circled the globe on the back of a new trend or hot topic of discussion include last summer's craze for downloading the voice of an ex-American footballer from an Old Spice advertisement. When the original aftershave commercial began to make an impact on Twitter, the company quickly put out custom-made videos for social media users. At least 120 videos were posted on YouTube over 24 hours, while the star, Isaiah Mustafa, busily replied to hundreds of tweets, including many to famous Twitter users, such as the showbiz blogger Perez Hilton.

Old Spice suddenly became YouTube's most popular sponsored channel to date, accruing 40 million views. A live "voicemail generator service" followed a day or two later, allowing users to tailor their own messages. When the public logged on to the right site, Mustafa, or "the Old Spice guy", would customise a message for their voicemail.

Another successful commercial campaign followed Kraft Foods' decision to hire a homeless American man called Ted Williams as the voice of their products, after Williams had given an eccentric online interview to a local news site in Ohio that quickly went viral.