Darwin Nunez hit back at his critics with four goals for Liverpool in the 5-0 win over RB Leipzig on Thursday night.
Mohamed Salah opened the scoring with a composed finish on eight minutes.
After sub-par performances against Manchester United and Crystal Palace, Nunez responded with four goals - his first strikes since becoming the club's record signing.
Asked if it was a perfect night, Klopp told reporters: "I would have bought it actually. It's really nice.
"You see everything. First half – good moments, lesser-good moments, not enough movement, we need to get used to how hard it is to play 50, 60, 70 minutes – and in the end 90 or 120. The human body is like this, you need to get used to it again.
"When we struggled a little bit it was always after three minutes' break we played football again, then a deep breather and play football again. And I wanted us to be a bit more hard with ourselves, go over that point, it's pre-season.
"And move more. I think we did that second half obviously. Hendo came on, Millie – they both were lively. Hendo all of a sudden as an eight, went in behind and we created chances.
"Then Mo gives Darwin the penalty and Darwin, Pandora's box was open. That's of course a perfect night for him."
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