The 20 year - old came through the ranks at Schalke and had developed into a key figure at the Veltins Arena after making his first - team debut in April 2014 .
The 20 year - old has cost City a reported $65 million .
The 20 year - old , who has cost City a reported $65 million , came through the ranks at Schalke and had developed into a key figure at the Veltins Arena after making his first - team debut in April 2014 .