The Rolling Stones have invited Adele, Lady Gaga, Florence Welch and Paloma Faith to perform with them at the British Summer Time Hyde Park festival on 6 and 13 July.
A source said: "The Stones would love to get Adele on with them. It would be a massive coup, even for them, because she's been a bit reclusive since her son Angelo James was born.
"She is the name they want to announce as their special guest and their invite should be special enough to get her out on stage.
"At the minute it's 50/50 that she'll do it, but Mick is quietly confident he can pull it off. They want to make the Hyde Park shows a highlight of their tour, and her appearing would make it really special."
The Stones - who invited Sheryl Crow on stage with them for a gig in Chicago on Friday night (31.05.13) - have also lined up collaborations with Lady Gaga, Paloma Faith and Florence Welch for their gigs at the London venue.
The source added to The Sun: "The group think female performers are a great complement for Mick ever since Florence Welch got on stage with them at the O2 Arena last year for Gimme Shelter.
"Gaga, Paloma and Flo would all do well in the Hyde Park shows, but Adele is the big prize this summer."
Tickets for the Stones at Hyde Park here.