"We looked up and thought 'Hoopla'!" Mueller told Germany's ARD television of the moment Portugal were 2-0 down after 32 minutes. "There was still a long match ahead of us and it was really hot in the sun."
Things got even hotter for Mueller a quarter hour later when he got entangled in an incident with Portugal defender Pepe that led to the World Cup's third red card.
Mueller said he felt Pepe's fist strike his head as both players tried to head a ball and the big German went crashing to the ground.
Pepe, angry at what he thought was Mueller's exaggerated fall, went over to Mueller on the ground and pushed his head into the German's.
Mueller jumped on his feet and the two shouted at each other for a tense moment before being separated. Pepe was sent off.
"I'd like to see it in TV," Mueller said. "I only hope that I looked okay. I felt a blow from his fist. But what happened after that I can't really remember, whether we were head-to-head or not. I just hope it didn't look stupid on TV.
"I didn't want to cheat," Mueller added. "I don't know for sure how I got out of there."
Mueller, who won the Golden Boot of the 2010 World Cup with five goals in six appearances, said he had not been looking for a clash with Pepe but was not about to back down against the defender either.
"I've experienced a number of things in international football matches over the last four years and I'm not the kind of guy who gets easily scared," said the 24-year-old Mueller.
The Bayern Munich striker, who has now scored 20 goals for Germany in 50 matches, said he and his team mates had a great time running up the score against Portugal and even lamented the fact they wasted several good chances in the first half.
"We had some good counter-attacks as well and could have even scored more if we took advantage of our chances," he said.
"It was great. Each goal that went in seemed to be better than the one before it."
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