The Hungary international winger is drawing interest this summer and it has been claimed that both West Ham and Rennes are talking to Freiburg about him.
The Breisgauers will not let Sallai depart cheaply though and will want a price they deem to reflect his true value to green light a move.
And a bid has already gone in for him, according to German daily Bild (via Fussball Transfers) and it has come in at over €20m.
It is unclear which club have put in the offer for the 26-year-old.
Sallai made 27 appearances across the course of an injury interrupted season for Freiburg last term.
He has now clocked over 100 outings in the Bundesliga for Freiburg and has also played his club football in Hungary, Italy, Cyprus and Germany.
It remains to be seen whether Sallai will be able to add England or France to that list in the coming weeks.
