Chelsea are hoping to sell before they buy a new left-back.
The Blues are keen to add a top player at the position this summer, with Leicester City's Ben Chilwell, Ajax's Nicholas Tagliafico and Porto's Alex Telles being considered.
But they'll need money to fund a deal, especially with Leicester demanding £85m for Chilwell.
The Sun says Chelsea will look to sell Emerson and Victor Moses to raise funds.
Emerson is wanted by Juventus and Inter Milan, the club Moses is currently on loan with.
A £9.25m fee has been agreed with Inter for Moses, while Emerson would cost around £20m.