League leader Liverpool travels to face the defending champion at the Etihad on today with seven points separating the two sides in the table, Sky Sports reported.
Tottenham moved above City into second place on Tuesday with a 3-0 win over Cardiff but Klopp insisted the champion is still the team to beat this season.
"It is a normal game against Manchester City but a very difficult one, one of the most difficult you can play in modern football," he said.
"They are a really strong football team with an outstanding manager. Before you play them, you never know.
"We have to be prepared as good as possible, be brave, full of desire and angry again like in all the other games.
"The opponent is, for me, still the best in the world."
Pep Guardiola believes his side cannot afford to drop points against Liverpool if it is to defend its Premier League title this season, but Klopp has played down talk of must-win matches.
"You will have to ask Pep why he said it," said Klopp. "If we were 10 points behind after the game, then would I say 'we can still catch them'.
"Of course not, it is difficult with the quality all the teams have. But it is just not important – it is the second of January.
"It is a very, very, very important game for both teams. I would use it as motivation.
"These are six-point games, when we play against each other it can go in all directions. It is a motivation for them, 100 per cent."