NEW YORK — After a hard fought first-round win at the US Open, Madison Keys let out a scream that resonated all over Arthur Ashe Stadium. As she walked to the net to shake hands with Alina Korneeva, the camera shifted to her player’s box, where her husband and coach Bjorn Fratangelo cheered her opening round victory.

The celebratory moment turned into a 5-second product placement for online car seller Carvana, as Fratangelo was decked out in apparel showcasing the company’s logo.

Keys’s team is far from the only one that flashed brand logos from the box at the US Open. Iva Jovic’s team has been decked out in the Carvana shirt and cap, while Ben Shelton’s team has worn just the caps; Ukrainian star Elina Svitolina’s team wears jackets with the logo of Ukrainian software brand MacPaw; and Aryna Sabalenka’s coaches have worn caps promoting health supplement brand IM8.

It’s a clear sign that coaches have turned into another avenue in tennis for advertisers, in part because tournament rules only allow for a limited number of sponsorships on players’ clothing. The Grand Slam rulebook allows for a maximum of two commercial logos displayed on a player’s kit, in addition to the logo of the apparel manufacturer.