Singing competition show The Voice released a promo clip this weekend featuring new coaches Gwen Stefani and Pharrell Williams.

The video is set to Stefani’s hit song “Hollaback Girl,” which she co-wrote with Williams, reported seattlepi.com. The song choice underscores the close relationship between Stefani and Williams.

“[Stefanie and I] always had a special connection, and it was always through music that we recognized each other’s admiration and the depths [that] there was such potential…” said Williams, according to NME Magazine.

The two will be replacing former coaches Cee Lo Green and Christina Aguilera. Veteran coaches Adam Levine and Blake Shelton will also be returning for the new season.

Shelton appears to be cautious about his new co-workers.

“You’re not gonna see Adam or I be polite about it,” said Shelton to CMT about accommodating Stefani and Williams. “Because we have a job to do there, and the gloves come off, mostly in the blind auditions. If we hear an artist up there we think could win this thing, there’s no telling what we’re gonna say or do. And hopefully, they’ve studied up enough on the show and know that’s what’s gonna happen, and they’ll come in swinging, too.”

The Voice will be returning to NBC for its seventh season on Monday, Sept. 22 at 8/7c.