Ballack set for first Leverkusen start
The 34-year-old midfielder, who made his comeback as a substitute last week, said the only way to improve his fitness was through match practice.
"No test and no training can give you the fitness you get in a match," Ballack said.
Ballack's team mate, striker Patrick Helmes, could be on his way out after he was cut from the Leverkusen squad for the Hanover game by coach Jupp Heynckes.
"In the past few days he has been far too busy with his transfer prospects," Heynckes said.
Werder Bremen have signed talented Serbian teenager Predrag Stevanovic from Schalke's youth team as they bid to inject new blood into their disappointing season so far.
The 19-year-old, who has played for Serbia's U17 and U19 teams, signed a contract until 2014.
"He is a very talented player for the offensive midfield. We are convinced we can further develop him," said Bremen's managing director Klaus Allofs.