Britney Spears' sons have been learning how to sing and dance by watching her.

The 'Perfume' singer is preparing for the start of her two-year residency in Las Vegas on December 27 and says sons Sean Preston, eight, and Jayden James, seven, have picked up plenty from her rehearsals.

Britney told E! news: ''Preston, he's already dancing up a storm. He shows all my dancers how he can dance. It's really funny. [Jayden] is actually the singer. He sings a lot.''

The star has been in intensive training for the shows and subjected to a gruelling rehearsal schedule, but is pleased with how things are looking ahead of the grand unveiling.

She added: ''I've been through the wringer. But it's coming together and it's going to be worth it. I really feel that this is my best show I've ever done.

''I think the show takes you on this fun rollercoaster of uplifting things and then moody stuff that grabs you and takes you in.''

Britney said one of the things that has helped give her a lift while preparing has been when she spots one of her sons in the crowd.

She said: ''I love when they're there. Last night, Preston was there and he lit me up when I saw him in the audience.''