NEW YORK: Nike, the sportswear brand, is seeking to prevent a potential Olympic medal winner from competing in a rival's kit, even though as a member of the US team in Rio he would be wearing a Nike outfit.

Nike alleges that Boris Berian, world indoor champion at 800m, violated the conditions of a short-term contract when, after that expired, he agreed a deal with its competitor New Balance inside the 180 days during which Nike retained the rights to match any competing offer, the Wall Street Journal reported.

Until recently Berian was working in a burger store, but Nike claimed in court papers that it "would suffer serious, substantial, and irreparable harm if [Mr. Berian] endorsed the products of a competitor".

He has been running in New Balance shoes since January but the aggressive approach of Nike – "Nike values its relationships with athletes and we expect them to honour their contractual commitments," the company said in statement – could see him sitting out the US Olympic trials at the start of next month.

"If Boris has to compete with a Nike affiliation, as Nike is claiming he has to, he will think twice about doing so," his agent said.

Ironically, he would have to do just that if he was a member of the US Olympic team, with which Nike has a sponsorship deal extending to 2040.

His lawyer noted in a court document: "If Mr. Berian makes it to the Olympics he will be training, competing, and essentially living in Nike gear for the entire 2016 Summer Olympics – except for footwear – regardless of whether he is under contract with Nike, a Nike competitor, or no one."

Nike's approach to sponsorship has long focused on athletes while its biggest rival Adidas has emphasised events.

During the last Olympics, in London in 2012, research showed that at one point Nike dominated conversations on the internet, with 7.7% of the Olympics-related conversations associated with it, while Adidas was associated with only 0.49% of such conversations.

But that research did not mention the tone of those conversations; it remains to be seen how fans react to a global brand suing an athlete who declined to accept its offer.

Data sourced from Wall Street Journal; additional content by Warc staff