Mikel Arteta's side inflicted a rare defeat on the Reds in July, after Klopp's side had won their first league title in 30 years, and then won again on penalties in the Community Shield last month after a 1-1 draw at Wembley.
Klopp, who can see the improvement the Spaniard has made since taking over in December, admits the league defeat was down to an even rarer drop in intensity levels.
"You can see the balance between defence and offence is really good. He did an impressive job and changed the whole mood in the club.
"I don't know exactly what the mood was before he arrived but I don't think a lot of people thought before the end of the season he would win a competition, and he did that by winning the FA Cup.
"It is a tough opponent, 100 per cent. It is their defensive structure, they defend properly. All the players are involved in their defending.
"They probably defend in a 5-4-1 and when you have quality players in the team, for the other team it is a pretty tricky situation, then with the speed they have for the counter-attack it can cause trouble."