The Top 8 contestants in "The Voice" season 8 gave their hearts and souls during the Performance Night for week 4, but it was not the only highlight of the show. During the Monday episode of the long-running reality singing competition, the past coaches of the show returned to help the current coaches in honing the skills of their remaining artists. 

Two-time coach and Hip Hop and R&B sensation Usher returned to help Coach Adam Levine with his sole contestant Joshua Davis. Usher appeared during the fourth season and helped Josh Kaufman win the title in season 6.

Last season's coach Gwen Stefani also returned as an Advisor for Team Christina and Team Pharell, who both have two contestants each under their wings. On the other hand, original "The Voice" coach Cee Lo Green returned to help Blake Sheldon in coaching his three remaining contestants.

Meanwhile, former coach Shakira was also invited to return but she could not travel out of Barcelona yet since she just gave birth to her new baby. 

The first performance for the night came from Team Blake's Hannah Kirby, who sang Tina Turner's "We Don't Need Another Hero." She was immediately followed by Team Adam's only contestant, Joshua Harris, who performed Sting's "Fields of Gold." 

Then, Kimberly Nichole from Team Christina sang her own rendition of "Creep" by Radiohead. Her performance was followed by another Team Blake member Meghan Linsey, with her powerful rendition of the 1969 Beatles' song called "Something." 

The classic "Over the Rainbow" was later performed by Team Christina's India Carney, which was immediately followed by an amazing rendition of Lynyrd Skynyrd's "Simple Man" covered by Team Pharell's Sawyer Fredericks. 

Team Blake's final performer for the night and only country singer Corey Kent White sang Bad English's "When I See You Smile," while the final performance came from Team Pharell's Koryn Hawthorne, who performed Alicia Keys' "Girl On Fire." 

Among all the performances, only Team Adam's Joshua Davis and Team Pharell's Sawyer Fredericks managed to get to the Top 10 of the iTunes chart, which means that they have a good chance of moving to the next round. 

The Results Night for week 4 will be aired on Tuesday on NBC.