At first Max Galuppo, university student, of Bloomsbury, New Jersey, didn't believe it.
Then he saw a picture of himself next to the portrait.
And he had to accept that he looked remarkably like the figure described as Nobleman with Dueling Gauntlet.
Max and his girlfriend were strolling through the Philadelphia Museum on November 11 when they stumbled across the portrait.
Max's girlfriend Nikkie Curtis told ABCNews.com: "We went into the armor exhibit and he loved the helmets. He was completely oblivious to it, and I walked past it and was like, 'Do you see this painting right now? It looks just like you.'"
Max said: "To be honest, I didn't see it. I didn't see the resemblance. Then I saw the picture of me next to it, and you can't deny that."
Max has been asked to pose with the 1562 portrait dressed in the same way.
He's thinking about that while he tried to find more information about the painting and the nobleman it depicts.