Grubauer gained attention while competing for Germany in Division I of the 2010 World Junior Championships in Megève and Saint-Gervais-les-Bains, France. Germany placed first in their group, winning all five of their games in order to put them back in the Top Division for the 2011 World Junior Championships. Germany's success was largely due to the play of Grubauer, who posted a 0.64 GAA and a .974 save percentage in five games.