 Complete the following phrase:  In 2009, he made his World Cup debut. He became world champion by winning gold in the 15 km mass start race at the Biathlon World Championships 2017 in Hochfilzen. He also won three more gold medals, two for being part of the German Biathlon World Championships 2010 mixed relay team in Khanty-Mansiysk and the German Biathlon World Championships 2017 mixed relay team in Hochfilzen, and one gold medal as part of the German 