With Real Madrid and Manchester City also in Group D, the BVB coach feels Tuesday's encounter will prove crucial for his side's chances to make it to the knockout stages, and is confident they have put last year's poor performance in the competition behind them.
|15/2||Dortmund are 15/2 with Bet365 to beat Ajax 3-0 on Tuesday evening
"There is a feeling of us having to win this match against Ajax on Tuesday or we are already out again," Klopp told reporters at a press conference.
"We have defined our way of playing successful football and we will not change things too much for the Champions League.
"Our problems last season did not have much to do with our playing style but were rather a result of lacking experience. That's what we want to work on.
"We have gained a lot of international experience now and we have also learned that our football is working. But we also learned that we need to make fewer mistakes to get results.
"We made bigger mistakes in Europe last season than in the Bundesliga – and unforced ones at that."
Dortmund's clash with Ajax at Signal Iduna Park kicks off at 19:45GMT.