Ant and Dec: A hit with young audiences

But it will face a stiff task to match the popularity of SM:tv, which is hosted by Ant and Dec and was attracting up to twice as many viewers as Live & Kicking.

The first airing of the three-hour Saturday Show featured an appearance from pop singer Sophie Ellis-Bextor plus games including Karaoke Karnage, where stars see their songs "butchered" by audience members.

Meanwhile SM:tv featured a star-studded line-up with Britney Spears, Robbie Williams and Victoria Beckham on the same day.

Behr, 26, has said The Saturday Show would have "the right content, style and attitude" to challenge ITV1.

Past BBC Saturday morning shows

Swap Shop Saturday Superstore Going Live Live & Kicking

The show will have a "late-night studio" feel along the lines of Channel Four's TFI Friday and So Graham Norton, she said.

"We know what we're up against. Ant and Dec have been friends for years and their timing is perfect."

Behr made her name presenting Channel 4's notorious late-night youth show The Word, but has appeared in no enduring hits since.

She also said her lack of children's TV work would not be a big problem.

Her co-presenter Mace is a rising star who is so far best-known for his madcap style on Top of the Pops Plus.

The show will feature a five-strong house band who were found through a nationwide talent search.

'Worth getting up for'

A BBC spokeswoman said The Saturday Show would be "more of an experience to watch" with a Glastonbury-style stage and the audience sitting in "waltzer-style" pods with interactive voting pads.

"We might get Dani Behr in a nurse's uniform, which is worth getting up for," she said.

Live & Kicking began in 1993 and was originally hosted by Emma Forbes and Andi Peters, before Zoe Ball and Jamie Theakston replaced them three years later.

But a ratings slide that started when Emma Ledden and Steve Wilson fronted it could not be stopped by Katy Hill, Sarah Cawood, Ortis Deley and Trey Farley.

Ant and Dec are currently achieving audiences of up to two million for ITV on Saturday mornings.