But Monday's match in Porto Alegre takes place two days after the start of Ramadan, when for a month devout Muslims fast between sunrise and sunset.
Asked if his players were observing Ramadan, Halilhodzic said it was a matter for individuals and it was disrespectful of reporters to raise the question.
"It's not the first time I have had Muslim players in my team. I myself am a Muslim. I've always let them be free, this is a private question and when you asked this you lack respect," the Bosnian-born coach said.
"The players will do as they wish. This is private. You should talk about football and nothing else. Stop asking me about Ramadan otherwise I'll get up and leave."
Algeria defender Rafik Halliche also batted away the issue.
"Are we going to observe it? Now we have to think about this match against Germany," Halliche said.
Some of the Algerian players - a number of whom were born in France to Arab immigrant parents - have nonetheless been proud to show their faith on pitch. After their goal against Belgium, they celebrated by kneeling in prayer.
Halilhodzic made no bones about the fact that Algeria will have to play the game of their lives to beat the three-times world champions and progress to the quarter-finals.
"Tomorrow is a very serious opponent. They are a very good candidate to be champions again. We have to control the ball. You know their mentality, their fitness. For us it's going to be very challenging.
"Germany is the favourite obviously but the Algerian team is able to surprise you. We are confident, we have to been improving in every match. Tomorrow we will have to be exceptional. Tomorrow we have nothing to lose. We are ambitious."
Inevitably, the subject of "The Disgrace of Gijon" - an episode in the World Cup in Spain 32 years - came up again.
In 1982, Algeria beat West Germany but were denied a place in the next round after the Germans and Austria played a half-hearted match in which the former took the narrow victory they needed to go through along with their beaten opponents.
Accusations of collusion between the close European neighbours have dogged them ever since.
German coach Joachim Loew said on Saturday all that was irrelevant. Halilhodzic at first also said it was "history" but pressed again on the subject, said: "My players have to be motivated. They'll do everything to get their revenge."
Algeria have won many admirers on their way to reaching the last 16 of the tournament at their fourth attempt.
Their 4-2 thumping of South Korea - also in Porto Alegre - was a high point and made then the highest-scoring African team in a single World Cup game.
"We will prepare this match as the most important match in our career. We will do our utmost, we will give it our all and we will try to leave this wonderful championship as well as possible," the coach said.
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