The Reds manager Aitor Karanka has previously worked with the forward at Middlesbrough, and he wants to reunite with him again next season.
The 24-year-old started his professional club football at Forest before he switched to Chelsea in 2012.
He spent a loan session in 2014-15 at Boro and later joined on a permanent deal from Chelsea in January 2017.
Karanka signed him for Boro at that time, and the Spaniard is keen to work with him again.