Jordan Henderson and Joel Matip are both in doubt for Liverpool's Premier League opener.
Both players missed the Community Shield loss to Arsenal on Saturday.
And Klopp has doubts they will be ready in time to face Leeds United on September 12.
"For that we have to see when he trains," Klopp said.
"I think Joel and Hendo will be in parts of team training next week and we will see. Of course, the longer they have the better the chance is, but I don't know in this moment."
