Claudia Winkleman and Tess Daly are to take part in a danceathon for Comic Relief.
The "Strictly Come Dancing" presenters will be pushed to their limits with the endurance test, which is set to be the longest-ever dance challenge in Red Nose Day history and will run from March 11 through to 12.
Claudia and Tess will strut their stuff to Radio 2's soundtrack and have all their moves streamed live on the BBC Red Button - where viewers can also see the music videos appear in conjunction with the radio broadcast - and each show on the station will also follow their progress.
Red Button viewers will also be able to send messages of support to the pair, which will scroll across the screen.
Claudia - who hosted a six-hour Danceathon for Comic Relief in 2015 - thinks the epic endurance test will be "hilarious" for viewers to watch because neither she nor Tess are great movers.
She said: "I'm so excited to be taking on this epic Danceathon challenge with Tess live at Radio 2 in the legendary Wogan House.
"I know it's going to be hilarious to watch because we're pretty bad dancers - I'm not very good at standing, let alone dancing.
"Thankfully we'll have each other and we're going to push through to raise as much money as we can for Red Nose Day.
"We love Comic Relief and believe in everything they do. We've seen first-hand how the money raised provides a lifeline for people living in the most desperate situations, and we're doing this for them. We want people at home to come together, dig deep and support us through this because dancing for over 24 hours is going to be one hell of a challenge."
And while Tess, 49, is "proud" to be taking part, she's worried she and her 47-year-old pal won't be able to complete the danceathon.
She said: "I am so proud to be supporting Red Nose Day with Claudia. I just hope we have the stamina to "keep dancing" for over 24 hours straight!
"We were worn out during our first choreography session so it's no doubt going to be a tough challenge. But, we're doing this to raise money for Red Nose Day, so it will be incredibly special, and we'll be thinking of all the people that will benefit from all the amazing projects funded by Comic Relief.
"Doing this at Wogan House is extra special for me having worked with the great man, Sir Terry, himself many times."
The Longest Ever Danceathon with Claudia and Tess follows Sara Cox's 24-hour 80s danceathon in 2017 and Dermot O'Leary's 24-hour day of dance in 2015.
Red Nose Day takes place on March 15.