If there is a law of contemporary advertising, it is that athletes on holiday must never simply be allowed to lie by the pool. They must, instead, cause problems.

This principle has now been given architectural form by Under Armour and its agency, Mox London, in the shape of Hotel Armouré, a fictional luxury establishment where the guests include the footballers Ollie Watkins and Ferran Torres, and where the staff, led by a beleaguered manager played by Nick Mohammed, are subjected to considerable abuse. Mr. Watkins practices his golf swing from a balcony, sending balls raining down on sunbathers. Mr. Torres turns the swimming pool into an ice bath. The hotel slippers are monogrammed. The chaos is deliberate.

The campaign, which carries the tagline "Rest Less," represents the first work Mox has produced for Under Armour, the sportswear company based in Baltimore that has been attempting to sharpen its positioning against Nike and Adidas for the better part of a decade.

Matt Bolton, a co-founder and executive creative director of Mox, said the idea emerged from what he described as an obsession with footballers on holiday. "We delved in in a big way," Mr. Bolton said, "and dipped through some of the amazing images, like Zidane back in the 90s in his short shorts." The observation that elite athletes do not, in fact, rest during their rest periods led to the line. "One of our creatives said, 'They're just restless.' Then everyone just looks at each other and goes, 'Yeah, got it.'"

(One imagines the moment was less dramatic than that, but the industry does love a creation myth.)

The production, which involved shoots in Barcelona, Paris and Birmingham, was conceived from the start as a social-media campaign — an increasingly common claim, though in this case it appears to have been true. The spots were designed for scrolling; hand-picked creators were integrated into the storytelling rather than handed products to unbox; and the teasers were made to resemble promos for a prestige television series.

Only later did the work migrate, in an unusual reversal, from social platforms to television and cinema.

Tom Peel, who leads sportswear marketing at Under Armour, said the campaign was rooted in the company's broader "Be the Problem" positioning, which holds that athletes "challenge convention, push boundaries and refuse to accept the status quo." (What, you were expecting them to accept the status quo?)

The pool, it should be noted, was not actually cold. "The pool was steaming hot," Mr. Bolton said, "because we obviously had very precious footballers sitting in there for a few hours." The ice cubes were added in post-production. The golf balls, similarly, were ping-pong balls with dimples painted on.

Mr. Mohammed, who played the hapless assistant coach Nate Shelley in "Ted Lasso," brings to the role of Fergus a quality of suppressed hysteria that the material requires. He was not the agency's first thought for the part, Mr. Bolton acknowledged, but became the obvious choice once his name appeared on the casting list.

The hotel, though fictional, was branded with the thoroughness of a real hospitality property — notepads, towels, a gold plaque for Mr. Mohammed to polish. "It was about getting the balance right," Mr. Bolton said, "so it didn't feel like we were forcing the brand at every moment."

There is, of course, an Under Armour logo on the floor of the pool.

Original story published in The Drum: "From pitch deck to poolside chaos: the making Under Armour’s ‘Rest Less’ | The Drum"