The Portuguese coach was widely expected to make an appearance after a penalty strike from Ronaldo, a header from the star attacker and a headed goal from Raphael Varane ensured qualification for the Copa del Rey regardless of Jordi Alba’s late consolation.
Casillas, who has been out of action with a hand injury since mid-January and is expected to return two weeks into March, hailed the Portugal international’s impact and hopes this win mends wounds caused by their poor Liga performances.
"We decided it's a good time to bring up the captain," the Spain international said to reporters after the game. "We realize that we will not win the title, but it’s a good time to converse publicly with the Blancos fans considering our level in the league.
"This gives us more peace for the rest of the season. Barcelona did not look as good as Madrid. The team were brilliant defensively. Cristiano Ronaldo has also been crucial."
Casillas went on to hint that he wants the former Manchester United winger to stay at the Bernabeu despite reports linking him with a move away, and the skipper wants the win to propel the club on to better things this season.
"Real Madrid have beaten Barcelona tactically," he added. "Cristiano Ronaldo is proving its importance in the Real Madrid. He’s our most important player. He’s already demonstrated his level in other Clasicos, too.
"He will have to deal with [the contract] issue with the club, but for us it would be a joy."