Carey Mulligan and Gemma Arterton will star in a one-off Mamma Mia! spoof penned by Jennifer Saunders for Red Nose Day.
The pair will appear alongside Alan Carr, Miranda Hart, Philip Glenister and Sue Perkins in the sketch.
Mamma Mia Here We Go Yet Again! will see Bafta-winning actress Mulligan take on Sophie, the role previously filled by Amanda Seyfried, while Arterton will play Lily James’ young Donna.
Speaking on set, Mulligan said: “There’s so many brilliant comedians here today.
“Jennifer is so good at making you feel relaxed and the rest of the cast have all been so sweet and encouraging.
“It’s been a real honour to watch these comedy masters up close.”
Baptiste star Tom Hollander will appear as Andy Garcia’s Fernando, while Susan Calman will play Julie Walters’ Rosie.
Scottish comedian Calman said the sketch was “probably the silliest thing I’ve ever done for charity”, adding that it included “dancing, Birmingham accents and eating cake”.
The short film will also feature Rose Johnson as young Tanya, Lucy Montgomery as Tanya and Joe Thomas as young Sam, Bill and Harry.
The BBC’s Red Nose Day broadcast will also see the return of Bodyguard’s Gina McKee and Vincent Franklin, who will join Richard Madden in a previously announced skit.
McKee played the steely Commander Anne Sampson while Franklin was the mistrustful Minister of State for Counter-Terrorism, Mike Travis.
Comedian Sanjeev Bhaskar will join the ensemble for the sketch, which is likely to poke fun at the heavy topic and nail-biting tension of the BBC One series.
Fresh from his daytime debut on This Time With Alan Partridge, Steve Coogan will return as the ubiquitous north Norfolk DJ takes to the streets of Norwich to raise money.
Other sketches will include a Top Gear special featuring Andrew “Freddie” Flintoff, an edition of University Challenge hosted by David Baddiel, and a performance from Only Fools And Horses The Musical.
Live Red Nose Day coverage will be broadcast from Elstree Television Studios, hosted by Sir Lenny Henry, on March 15.