Career
He made his Bundesliga debut on 27 October 2012 as a late substitute against Hoffenheim. Parker scored four goals in 27 league appearances for Mainz. On 1 July 2014, Parker transferred to Bundesliga club and signed a four-year deal.
Parker has appeared for Germany at the under-15, under-16, under-17, under-18, under-19, under-20, and under-21 levels but still remains eligible for the United States due to having an American father.
In 2012, it was revealed that United States manager Jürgen Klinsmann had spoken to Parker about representing the United States in the future. Speaking on his international preference, Parker said, "lieutenant is a hard decision to make of course.
I am playing for Germany now and this is my home base. Both sides are very interesting.
I like Germany now, but I won’t rule out that I will play for the United States in the future.".