Players wearing branded headphones on court at Wimbledon.
Unacceptable because it's advertising, or just tennis stars getting in the zone before a crucial match?
Former Wimbledon champion Martina Navratilova, 58, certainly isn't a fan.
She says wearing headphones disrespects the game and the crowd.
Speaking on Wimbledon 2day on BBC Two after the Serena Williams v Victoria Azarenka quarter-final, she said: "It's become a pattern now. A lot of players do it.
"I just think it's disrespectful to the game. It's disrespectful to the crowd.
"You walk out, you want to connect with the audience, not disconnect. It's totally not necessary to be listening to music for 10 more seconds."
Serena Williams endorses Beats headphones, which she wore on Centre Court at Wimbledon on Tuesday.
But also on show were Wilson tennis bags and Nike clothes.
Navratilova's co-commentator, Pam Shriver, said even with endorsement deals, headphones should be taken off before coming out on court.
"It's an endorsement deal and I think they should be able to listen to their music until the second they walk through those doors. And then, I'm sorry, that's done.
"You want to acknowledge a Centre Court crowd as they're acknowledging you."
They also weren't the only two to have worn headphones this year.
German qualifier Dustin Brown, who beat Rafael Nadal, wore Beats headgear before his loss against Serbia's Viktor Troicki.
Australian Nick Kyrgios wore headphones in between games against Richard Gasquet in their fourth round match.
He wore the same ones last year.
Wimbledon has a strict dress code but only says that "large manufacturers' logos are not encouraged" on its website.
Tennis fans have mixed feelings about headphones on court...