Voller believes Podolski may have to leave the club if he is to reignite his international career.
"You must not write Poldi off, he's not very old yet, at 29," Voller told Bild am Sonntag.
"Lukas is a very good player who always faces up to the challenge. Competition has got fiercer, but it says a lot that he is still always involved (for Germany).
"Of course it's an advantage for a player's self-confidence when he is playing regularly, though."
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