Schalke will decide in July whether to swoop for Chelsea defender Baba Rahman.
The Ghanaian spent last season on loan at the German club and he delivered some impressive performances for the first team.
However, the 22-year-old missed the second part of the campaign after suffering a knee injury at the African Cup of Nations.
It is hoped the left-back will recover in time for the end of pre-season and Schalke general manager Christian Heidel says the German club will wait to decide whether or not they should test Chelsea's resolve to keep Rahman with a concrete bid.