The sports duo will be joining forces, through the launch of a limited edition underwear collection, and have chosen to market it with a Facebook campaign, asking users to find their ultimate opposite, among the 700 million other Facebook users worldwide.

“This campaign is a way for us to celebrate the unlikely friendship that Björn and John share,” said Erik Jarnsjö, marketing director at Björn Borg, in a statement.

A test constructed by a professional psychologist will help Facebook users search for the person most different to themselves. Those considered to be absolute opposites will win a trip to New York City, and a meeting with the two tennis legends.

“The challenge was constructing a test which is complicated enough to reveal a person’s total opposite among 700 million people,” explained David Morgenstern, the psychologist behind the experiment, in a statement.

“For this to work, the results are based on how people react to images, which means there will be an endless number of different results and variables to compare. I’d call the test a combination of scientific seriousness combined with entertainment, scientific art.”

The underwear collection, consisting of four styles and launched in August, is inspired by the golden age of tennis, and has an “air of the eighties”, according to a statement released by Björn Borg on Wednesday.

The 1980’s was the era when the almost four hours long Wimbledon final between the two friendly rivals Borg and McEnroe took place.