Sadio Mane, Mohammed Salah and Roberto Fermino were converted on 59 minutes of a 1-0 victory in Holland on Wednesday.
With Liverpool ahead, Klopp used the five substitute rule in the competition by introducing Diogo Jota, Takumi Minamino and Zerdan Shakiri for the final half-hour.
The trio had opportunities to extend the lead, with Triumph placing the Reds second in the opening Group D table behind Italy side Atalanta, who won 4–0 against Mid Zealand in Denmark.
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And Klopp said: “You can see that it was an intense game for the three up front.
“It was tough for the first three, and I was really happy that we could do that (change them).”
“I was not in doubt about the quality of the boys (who had come). The game was very wild and we defended everyone together.
“We were defending 4-5-1 and both the wingers really needed to be involved in the defense. The moment you win the ball, then there are big places to counter attack, and we thought it makes sense to bring it afresh.
“The three who came are in really good shape, all of them really helped a lot.
“Shaq won the deflection, which was very special! It was unbelievable between the lines in both directions and Diago is a machine, he can punish opponents a lot in one-on-one situations.
“We did not eliminate them unfortunately.”
Jordan Henderson had already replaced Curtis Jones in the break, while Rice Williams – like Jones, making his Champions League debut – came in for James Milner at injury time.
And Klopp said: “I was really happy that we could make five changes. Millie only had cramps, but then you could bring Rhys and it was long balls (from Ajax) and Rhys is very strong in the air.
“There are some good stories in the game. It would not be on the front page of our history book, but it was a significant victory. “