Musiala turned in an assist from Gundogan to open the scoring in the first half and then played a key role in creating a match-sealing goal for his captain in the second.
The 21-year-old also scored a goal and was named man of the match in Germany's 5-1 tournament-opening win against Scotland on Friday.
Speaking Wednesday, Gundogan lavished praise on Musiala, who was playing in his city of birth in German colours for just the second time.
"For me he's incredible. It's such a joy to play with him. He's someone who can do the unexpected in every single situation and is such a difference-maker for our team.
"He is maybe the most important one at the moment for us and at such a young age as well, especially when it comes to creating, putting in the final pass and scoring goals which is something he's added to his game as well."
Germany coach Julian Nagelsmann also praised the young attacker, while revealing how he has guided Musiala through his young career.
Nagelsmann coached Musiala at club side Bayern Munich, before taking over as Germany boss last September.
"I have had a lot of meetings with Jamal at Bayern and now," the coach said, revealing his advice to the young attacker.
"He just should play like he's on any small pitch, anywhere, everywhere in Germany or England.
"He should think about playing with his friends and not think about the pressure. He did a brilliant job today as he did against the Scottish."
