Thomas Müller of Germany was a midfielder in the last World Cup in 2014. In this World Cup some news on the Internet claim that Müller will play as a forward. So, what will be his position during the tournament?
He mainly plays center forward or right winger, although he is often listed as striker. (source)
It's pretty safe to assume that he'll play on that position in the World Cup as well, but who knows what Joachim Löw got up his sleeve.