The versatile attacker was very pleased with the Bavarians' victory as he stressed that their opponents have proven in the past that they are no push-overs
The Germany international opened the scoring after only 12 minutes of play, with Anatoliy Tymoshchuk putting the match to bed in the second half after Freiburg had been reduced to 10 men, and Muller underlined the significance of Wednesday's victory.
"Winning here today was enormously important," Muller told the official Bayern Munich website.
"We've always made hard work of it here in recent years, and we've all seen exactly why Freiburg are so tricky. We set our sights high beforehand and we started very well.
"But strangely enough, just like the last couple of times it’s happened, when our opponents go a man down, we have more problems than when it's 11 against 11.
"But we're delighted about the three points."
Bayern resume their campaign on Saturday when they host title holders Borussia Dortmund.