Doubts had been raised about the 28-year-old playmaker's commitment to Real as his absence with groin and adductor muscle problems dragged on, with some suggesting he was saving himself for the tournament in South Africa starting in June.
However, he silenced his critics on Saturday when he came off the bench with 15 minutes left and netted a clinical winner in a 2-1 victory at Real Zaragoza that lifted the Madrid club back to within a point of leaders Barcelona with four games left.
"Jesus Christ was resurrected after three days and his follower Kaka needed 43," columnist Tomas Guasch wrote in As sports daily on Sunday in reference to the Brazilian's devout Christian faith.
"Kaka returned to greatness with a goal that could be worth a league title," he added.
When he entered the fray on Saturday, Real were searching desperately for the goal that would keep alive their hopes of catching champions Barca, who beat basement side Xerez 3-1 at home in the earlier kick-off.
Kaka linked superbly with fellow new signing Cristiano Ronaldo, sprinting on to the Portuguese forward's clever pass, and slotted home with an angled shot in the 82nd minute before racing to the Real bench to embrace his ecstatic team mates.
"The truth is it was a very special night for me after a lot of criticism," he told reporters.
"I have been playing football for many years and the worst thing is for people to doubt my injury," he added. "The best answer I can give is on the pitch."
TAKING MEDICATION
Kaka was asked about reports he had refused to take the drugs that would have allowed him to return to action earlier.
"I have no problem with taking medication to play," he said. "I have been taking it throughout the injury and I am continuing to take it.
"I am much better but I have to keep working. I played 15 or 20 minutes and I am improving physically little by little."
Marca columnist Ulises Sanchez-Flor wrote on Sunday that Kaka's contribution against Zaragoza had gone some way to repaying the transfer fee of around 65 million euros Real paid AC Milan for his services.
"If Real Madrid do eventually win the league we can say that his goal yesterday paid back a good chunk of the cash," Sanchez-Flor said.
"Kaka wanted to silence those who doubted his professionalism and who claimed he was delaying his return so he could arrive fresh at the World Cup," he added.
"It was worth the wait. In the few minutes he played he was the one who showed the most calm at the stage of the match when all the Madrid faithful were in agony."
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