The Athletic Bilbao forward was brought in in the 73rd minute of the game as a substitute for a hapless Ferran Torres. The 20-year-old made an instant impact, tantalizing both Nuno Mendes and Joao Cancelo on both sides of Portugal's defense.
His ability was on full display throughout the cameo appearance. Williams rose above Cancelo in the 88th minute to provide a headed assist for Alvaro Morata.
Spain secured their qualification into the top four of the UEFA Nations League with the last-ditch goal from the Atletico Madrid attacker.
Williams, who made his debut for La Roja earlier this week against Switzerland, certainly has the talent to become a superstar in the future.
For those who don't know, Nico Williams is the younger brother of Bilbao star Inaki Williams. However, the older brother represents the Ghanaian national team at international level.
Nevertheless, one assist, two shots on target, and 91 % pass accuracy is a mere statistical highlight of Williams' cameo appearance.
Fans hailed the youngster and claimed that the future is bright for the younger Williams brother as his growth continues.
Here are some of the best reactions after Williams' performance during Portugal vs. Spain:
Inaki Williams heaps praise on his younger brother and Spain star Nico
Inaki Williams recently praised his younger brother Nico for the abilities he possesses. Both players represent Athletic Bilbao at club level.
"Physically I am a bit superior. Even though I am eight years older than him, in the 100 meters I still give him a cramp! But, in one-on-ones, however, he is practically unstoppable. (His rise) is incredible.
"He is showing that he is (improving), he is gaining experience. In front of goal, he is improving a lot. And the truth is, if I were Luis Enrique, I would also call up Nico. He is a talent, a rough diamond that needs to be polished. "
"He has a lot of room for improvement and hopefully he can continue to improve.”
Nico has bagged two goals and assists each in six appearances for Bilbao as they sit fourth in the La Liga table.