The Blues have been in talks with their Bundesliga counterparts for several weeks over a deal for the Germany international, who is keen to join the club as soon as possible.

Havertz is currently with the German national team ahead of their Nations League fixtures against Spain and Switzerland this week.

Asked if he expected the 21-year-old to return to Leverkusen at the end of the international break, Bosz said: "Unfortunately our squad isn't set yet. I don't expect (Kevin) Volland and Havertz to train with us again.

"It's possible more players will transfer. We definitely still have to add some players."