Germany gave Cacau a new life and a new passport, and now the Brazilian-born striker wants to to pay that back with World Cup goals in the decisive Group D match against Ghana.
A loss to Ghana will result in three-time champion Germany's earliest exit from the World Cup.
"We know our qualities and have no doubt that we'll make it," Cacau said Monday, two days before the match at Soccer City.
Germany needs to rebound from a surprise 1-0 loss to Serbia which left Ghana atop the group with four points going into Wednesday's decisive round. Germany and Serbia have three points apiece and Australia has one.
Although Cacau has received no assurances from coach Joachim Loew, there are strong indications he will start for the suspended striker Miroslav Klose. He has been Loew's favourite backup striker in recent games.
"I've had no signal whether I will play or not and I don't know. Maybe I'll know more after training," the 29-year-old striker said.
"But if I get to play from the start, I will try to help the team with my strengths -- speed, ball control and finishing."
Cacau did not arrive in Germany on an expensive transfer to a big club and did not go through a hurried naturalization process to become available for the German national team.
He arrived in the country as an 18-year-old member of a dancing group with the help of relative. He didn't have a soccer contract, but he had the belief that he could succeed.
Cacau got a tryout with Turk Gucu, a Turkish-dominated club competing in Germany's fifth division and signed his first contract.
His performances in the amateur ranks caught the attention of Nuremberg, which signed Cacau for its second team. But he quickly gained promotion to the Bundesliga side. When Nuremberg was relegated, Cacau signed for Stuttgart and won the Bundesliga title in 2007. He extended his contract with Stuttgart earlier this year.
Born in Santo Andre outside Sao Paulo, Cacau could not keep a place in the junior side of the local giants of Brazilian soccer as a teenager. His mother was a divorced and working two jobs to feed her three sons.
Cacau, who got the nickname from mispronouncing his given name Claudemir when he was a kid, chipped in to the family budget by washing cars and trimming grass for neighbours and selling soft drinks and chips from a makeshift stall alongside a highway.
Then came his move to Germany and his 10-year rise that has taken him to soccer's greatest stage.
Cacau said he'd watched Brazil's matches in South Africa, but "more as spectator and not as a fan."
"I do have emotions but I watch more to see the tactics and the quality of play," he said.
Claudemir Jeronimo Barreto is "at heart" a German, his mother Ana Barreto has told German newspapers.
"Germany took him in her arms and gave him everything," she said. Her son often speaks of being "adopted" by Germany.
Cacau became a citizen in February last year and made his Germany debut three months later.
In 10 games for Germany, Cacau has four goals, including one in the 4-0 opening World Cup win over Australia, when he scored two minutes into his World Cup debut after coming on as a substitute for Klose.
"First game, first goal, I've put all that behind me, although it's all been very special," he said. "There is a very important game ahead of us and that's what I trying to concentrate on, while trying to forget the circumstances.
"There has been no more important game in my career, although it was similar when we won the Bundesliga title."
Cacau's presence has provided the German team with an element of Latin flair and when he's come off the bench he's often revived the team's game.
There's no doubt his relaxed, happy disposition is popular with the team. But his disposition shouldn't mask his drive to succeed.
"I want to win every match and you should see me in the locker room after we lose," Cacau said. "But you have to enjoy life and I am not going to change that."