Goalkeeper Casillas made a record-breaking 144th appearance in Europe's premier competition as Karim Benzema's goal was enough to earn a 1-0 Group B win over Liverpool and book the holders' place in the last 16.
Despite Real struggling match the excellent performance levels of recent weeks, Casillas enjoyed a relatively quiet outing against a much-changed Liverpool XI.
With qualification secured, Casillas is ready to focus on the battles ahead in La Liga and the Copa del Rey, while the FIFA Club World Cup also looms on the horizon.
"I am pleased for me but especially for the team," he said.
"We have done our homework - we managed to qualify for the last 16, so that now we can focus even more on the Copa del Rey and the FIFA Club World Cup."
Real were 3-0 winners at Anfield last month and came into the return match having dispatched rivals Barcelona in convincing fashion before last weekend's 4-0 thrashing of Granada.
Liverpool proved to be a more dogged opponent this time around, but Casillas was largely pleased with Madrid's efforts.
"Obviously we struggled to find the second goal, but we controlled most of the match," he said.
"We came off some tough games. We managed to find the goal and then we controlled the game.
"The defence has been great but Liverpool was the team that was supposed to risk more.
"All in all, we are going through a great period, but praise can make you weaker, so we have to be careful and go little by little."
Barcelona great Xavi will go neck and neck with Casillas if he features against Ajax in the Champions League and the goalkeeper is happy to take any record breaking in his stride.
He added: "Me, I wish I could play until I am 40 but competition is hard so I’ll do my best to compete and try to play every game."
