Felix joined the Colchoneros from Benfica in a €126 million (£113m/$142m) move over the summer, having enjoyed a fine season with the Portuguese giants.
And the teenager has picked up where he left off at the Wanda Metropolitano, with a series of impressive performances making him an instant favourite with the Atletico faithful.
He was once again on target on Tuesday to net his third goal in Atleti colours, breaking the deadlock in Russia three minutes after the restart following half-time.
In doing so, he has outstripped another former prodigy once on the club's books.
At 19 years and 325 days, Joao Felix is now the youngest player ever to score for Atletico in the Champions League.
The previous holder of that title was none other than Aguero, who netted his first against PSV in 2008 aged 20 years and 106 days.
By that point of course Aguero was already an old hand in the Spanish capital, with two full seasons under his belt after moving from Independiente on his 18th birthday.
The reason for the Argentine's delay in opening his account was that Atletico had to wait until the 2008-09 campaign to break a dismal run of 11 years without Champions League football.
It took Aguero just nine minutes of that PSV clash to score his first goal in the competition, and he hit again for good measure in the 36th minute as Atletico cruised to a 3-0 victory in Eindhoven.
He would eventually finish his maiden Champions League campaign with three strikes as Atleti went out in the last-16 phase.
Much has changed since those days, with the Colchoneros now perennial challengers in the competition's final stages under the tutelage of Diego Simeone.
Felix will hope there are plenty more goals to come this season in Europe as Atletico set their sights on the trophy, which has escaped their grasp twice in the final against rivals Real in 2014 and 2016.