'The Voice' Season 8 News: Past coaches Gwen Stefani, Usher and Cee Lo visit

Great news for all "The Voice" fans: big celebrities who served as past coaches reunited with the current coaches in one star-studded episode of the popular American singing reality show.

It's a grand reunion of sorts for "The Voice" family, as former coaches Gwen Stefani, Usher and CeeLo Green returned to the show to serve as guest mentors for Season 8's Top 8 contestants.

It may be an unusual pairing, but country superstar and current "The Voice" champion coach Blake Shelton paired up with CeeLo Green to come up with great performances for Team Blake's three remaining artists.

Contestants Corey Kent White, Hannah Kirby and Meghan Linsey were coached by two diverse mentors as they tried to make it to this season's Top 6.

In an interview with Extra, Shelton said he stayed in touch with Green even after the latter left the show.

"People think Adam and I are the odd couple, but to me CeeLo and I are… when we see each other we just laugh… we never stop laughing," the country superstar told Extra.

"Maroon 5" frontman Adam Levine meanwhile paired up with R&B superstar Usher to mentor his last remaining artist, Joshua Davis.

"Usher is really incredible. I was really caught off guard and blown away by his sincerity and his passion… the way he really connects to somebody," Levine said about the guest mentor.

Award-winning singer and producer Pharrell, as well as vocal powerhouse Christina Aguilera, for their part, enlisted the help of "No Doubt" lead singer Gwen Stefani.

Pharrell were all good words for Stefani, who is also his close friend. "Her thing is style, so even when she talks about technique, it's about style," Pharrell said about Stefani.

"The Voice" will reveal its Top 6 contestants for its eighth season during its broadcast on Tuesday.