“I expect that he will not come back,” Bosz said Monday of Havertz, who was joining up with Joachim Loew’s Germany squad.

Havertz has been heavily linked with a move to Premier League Chelsea and Bosz stressed nothing was confirmed. “It is only my expectation,” he said. “It could always happen that it does not work out.

“But negotiations have been so long, I assume as coach that the probability is greater that he won’t come back.”

The same applies to former Germany player Volland, who is on the brink of a move to Ligue 1 side Monaco.

“It is, as said, all possible in football,” said Bosz. “But if you ask me, I’ll say I’m not relying on him any more.”

Leverkusen begin their Bundesliga campaign away to Wolfsburg on September 20 after opening the season in the German Cup against minnows Eintracht Norderstedt a week earlier.