The battle is on in "The Voice' Season 7 as the coaches recruit team mentors for the reality TV singing competition.

Fifteen-time Grammy-winning singer, songwriter, pianist and record producer Alicia Keys just revealed on Twitter that her "friend Pharrell" has just invited her to be his team's mentor on the hit NBC show. Pharrell himself was a mentor when Usher was a part of the show's coaching roster.

Meanwhile, new coaches Gwen Stefani and Pharrell seem to be enjoying their tasks as coaches and have honed their recruitment strategies. The "Happy" singer tends to hone in on musical identity, rather than how contestants sounded technically. On the other hand, Stefani prioritizes technical ability, and is ready to share critiques about stage presence, emotional delivery and vocal styling. Stefani is admittedly not a fan of "vocal Olympics" or when singers try too many runs or change up melodies for a rendition that is uninteresting, "I'm sensitive to that," she said.

Stefani also takes a more lighthearted approach when trying to recruit contestants. While former coaches Christina Aguilera and Shakira often touted their girl-power sensibilities and maternal instincts to lure female contestants to their side, Stefani would playfully say, "Do you like clothes? I have so many clothing lines, it's crazy! I can hook you up!"

Veteran coaches Blake Shelton and Adam Levine's love-hate bromance is still on, as evidenced by their on-camera antics. When the show began, Levine greeted Shelton with a thumbs-down, while Shelton was quick to make fun of Levine's patterned shirt, asking, "What time is bowling practice?"

All four coaches have picked their team mentors. Levine will have legendary Stevie Nicks by his side, while Shelton will be working with country group Little Big Town. Stefani will be teaming up with husband Gavin Rossdale of the British rock band Bush.