Mexico were more or less having their way with Germany's defensive half of the pitch, with the Bender brothers struggling and their back line faring little better.
Half an hour into the match, though, Goretzka left with an injury, and manager Horst Hrubesch put on Gnabry in his place.
He didn't score another goal, but almost every time he got on the ball he was creating a scoring chance, either taking a dangerous shot himself or playing in a teammate making a supporting run.
All on his own, Gnabry kept Mexico's defense completely off balance, and when he forced a corner with yet another dangerous shot in the 78th minute, Mexico over-committed to marking him out -- and Matthias Ginter was able to score the equalizer because of that extra space.
He was something of a wild card, an uncertainty coming into the tournament, but if they can get more of that level of quality from him, Germany are going to be a lot tougher to beat -- and might even become a favorite to win gold.