Both acts have gaps in their touring schedules...
If you were a betting person, you'd do worse than to put a few quid on both Coldplay and Madonna headlining the world's biggest music festival next summer.
After all, Coldplay are touring Europe right around that time, and have a few days off in their schedule around the time Glastonbury is on at the end of June.
Madonna, too, is taking her 'Celebration' tour around the world right up until the end of April - and what better headliner than one of the biggest pop stars of all time, celebrating four decades of hits?
However, Glastonbury boss Emily Eavis has quashed all rumours currently flying around, and is adamant that no names will be revealed until the new year.
Eavis told the BBC podcast Sidetracked that the line-up for 2024 was still "up in the air", although she did hope that there would be two female headliners - and also that a major female artist has already been booked for the Sunday afternoon 'Legend' slot.
Over the weekend, she posted on Instagram that the rumours currently doing the rounds - some have also speculated that Dua Lipa would headline one of the nights - are unfounded.
"As always, there is much speculation and excitement about who is playing at Glastonbury," she wrote. "We are working on the line-up day and night at the moment, but it's still changing every day. The story about our confirmed headliners is untrue.
"As always, we love your enthusiasm and guesswork - but accurate news on headliners will be with you sometime in the new year!"
The festival takes place from June 26th -30th, and tickets were meant to go on sale last week but were pushed back by two weeks after some people claimed that they were having trouble registering.