NBC will inject more star power into “The Voice” when it returns in September for its ninth season. It’s been confirmed that Selena Gomez will join the cast as an adviser.

Each season, “The Voice” has its usual quartet of celebrity judges. As previously reported, Gwen Stefani will reclaim her big red chair after Christina Aguilera took over for her in Season 8. She’ll join Adam Levine, Blake Shelton and Pharrell Williams in selecting and coaching a group of singers through the competition.

While the four will make up the show’s regular judges, Gomez will join as a celebrity adviser for Team Stefani at some point in the season. In Season 8, which saw 16-year-old prodigy Sawyer Fredericks take home first place, celebrity advisers included Nate Ruess and Reba McEntire. According to People magazine, Gomez will likely be joining the show to help promote her album "Revival," which drops Oct. 9.

While Gomez is a big get for “The Voice,” she’s not the only celebrity singer who will grace the coaches and contestants with their presence in Season 9. It was recently revealed that Rihanna has signed on as a guest adviser at some point in the season. However, as E! Online notes, her role will be slightly different from Gomez's. The latter is only going to be advising Team Stefani, meaning there could be three more people joining the show at some point. Rihanna, however, will be an adviser to all four judges, a bit of a floating utility player for Levine, Shelton, Stefani and Williams.

“The Voice” premieres Sept. 21 on NBC. What do you think about Selena Gomez and Rihanna joining “The Voice” as celebrity advisers? Comment your thoughts below or tweet them to @TylerMcCarthy.