The Argentina star has not featured this season due to a calf injury sustained in pre-season but was named in the travelling squad for Barca's opening Champions League group game at Signal Iduna Park.
Valverde has been pleased with Messi's training performances but will not make a decision on whether his captain will start the match until closer to kick-off.
"We'll decide before the game," he said. "It wasn't very clear a week ago if he could come, but he was with the team in the last few training sessions, finishing well, taking the fear of pain out of his mind. We'll see what we do."