The Portugal international feels Wednesday's match will help Madrid get back on track after a tricky start in La Liga. Alvaro Arbeloa was equally happy with the victory.
Los Blancos were beaten 3-2 in the first leg, but early goals from Gonzalo Higuain and the Portuguese winger put the Santiago Bernabeu side 4-3 up on aggregate.
Lionel Messi then pegged one back from a free kick, but it was not enough for Barca as Madrid came out victorious on the away-goals rule.
"We started well and we scored two quick goals that gave us confidence," Ronaldo was quoted as saying on the club's official website. "We played well and created many chances. In the second half we slowed the tempo because we were tired, but we deserved to win.
"We won an important trophy. It gives us confidence and we have to celebrate it. We cannot slip up in La Liga because we know that Barcelona are very strong."
Fullback Alvaro Arbeloa was equally pleased with Madrid's display and urged his teammates to show a similar attitude in La Liga.
"I’m very happy, we played an amazing match. We should have won by more because we created many chances; the important thing was to win the match and give our fans something to cheer about, which they deserved.
"This is the attitude everyone wants and we are the first to know it, not just against Barcelona, but every week in the Liga."
Madrid locks horns with Granada on Sunday.
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