The Portuguese broke the deadlock in just 10 minutes of the semi-final first leg before finding the back of the net twice more after the break.
The hat-trick was his 42nd in football – a quite staggering achievement from arguably the world’s greatest player.
Aside from Ronaldo, Sergio Ramos was the other Real Madrid star who caught everyone’s attention – but not for the same reason.
The Spaniard pushed up for a corner during the tie, as he so often does, and attempted to get his head on it, as he so often does.
Lucas Hernandez kept an eye on Ramos and marked him for the corner as the Spaniard set about charging into the area.
However, instead of negotiating the Frenchman, the Real Madrid man collided with the defender, leading with his elbow.
Replays showed him hitting Hernandez on the back of the head, and he was lucky to not have been sent off for the 23rd time of his career.
(He picked up his last red card just last week in El Clasico, as Madrid were beaten 3-2 by Barcelona at the Bernabeu).
As to be expected social media was really not impressed with Ramos on Tuesday: