Cee Lo Green is amazed by Christina Aguilera's vocal ability.

The pair co-judge with Adam Levine and Blake Shelton on US TV talent show The Voice.

Although Cee Lo has some incredible range himself, he believes that Christina is a powerful singer.

"Technically, she's probably one of the greatest vocalists of our time," he told Extra.

There is major speculation that Christina is somewhat of a diva on the show.

Cee Lo discounts these rumours and claims that Adam is actually the biggest prima donna on set.

"People would assume that it's Christina, because she's the only girl but, Adam has a nickname, we call him a he-va!" he laughed.

Cee Lo is currently preparing for the release of his album with rap group Goodie Mob called Age Against the Machine.

He spoke previously about his excitement over the record.

"The Goodie Mob, we definitely are reunited. And we've been working on that album really vigorously and it's coming out very well," Cee Lo told MTV News. "I think people are going to be very pleased."

The Voice will premier in America on September 10.