If the contestants on NBC's new singing competition 'The Voice' don't achieve success, it won't be due to a lack of mentors. In addition to its four celebrity coaches, the show is preparing to bring in R&B vocalist Monica and Australian pop singer Sia to help guide its aspiring singers.

The new mentors -- along with country star Reba McEntire and Maroon 5 music director Adam Blackstone -- will join established coaches Cee Lo Green, Christina Aguilera, Adam Levine and Blake Shelton in the coming weeks, according to reports.

The new advisers will help contestants choose songs and provide general guidance during the four-week "battles" phase of the competition. Monica will join Green's team, while Sia hooks up with Aguilera, McEntire joins Shelton and Blackstone joins Team Levine.

If the first episode of 'The Voice' is any indication, the program is going to provide lots of thrills over the next several weeks.

Watch Highlights From the First Episode of 'The Voice'

More From PopCrush