Germany's third-top scorer of all time, with 49 goals in 97 appearances, had been seen as past his best after netting only three goals for Bayern Munich last season.
His last international strike, against Russia in October, had sent Germany to the finals in South Africa.
But even before scoring his 11th World Cup goal and Germany's second in Durban, Klose knew he would hit the target.
"I never doubted myself, have never done it and will never do it. I know my strengths," the striker told reporters, without revealing what his wager with himself was.
"This is one of my strengths, being able to be ready when it matters," he said.
Klose, who also scored three goals in the 2002 World Cup opener and two in their first match at the 2006 tournament, said despite being on the bench at his club for much of the season, playing for Germany always gives him a special feeling.
VERY SPECIAL
"Being needed by this team means so much to me," he said. "I've always felt needed in this team and that is very special."
Klose, who was picked to start ahead of the in-form Cacau, could not have chosen a bigger stage to silence his critics back home, with close to 28 million Germans glued to their TV sets when he headed home a Philipp Lahm cross in the 26th minute.
Klose hugged captain Lahm for about 30 seconds, his relief visible to all.
"I was so focused I cannot remember what Lahm told me. It was a great feeling just to have him in my arms for 30 seconds," he said, laughing out loud.
Germany coach Joachim Low praised Klose as well as Lukas Podolski, who was also heavily criticised before the tournament after a mediocre season in which he scored only twice for Cologne. Podolski had fired in Germany's first goal.
"This discussion about Klose and Podolski is one that I never understood. Seriously, I never got it. I was always convinced of their strengths," said Low.
"Some coaches may want a different type of player... but for me it was always an issue of reminding them of their strengths. I don't want new strikers because they (Klose and Podolski) fit in my overall philosophy."
