United are in the midst of a nine-game winning streak in all competition and 15 matches unbeaten in total ahead of Sunday's Premier League clash.
Liverpool, on the other hand, have gone three games without a win following their first-leg loss to Southampton in the EFL Cup semi-finals midweek.
Klopp, however, believes Liverpool - who can regain second position and extend their advantage over sixth-placed United to eight points - are ready for their test in Manchester.
"Whatever we do, never doubt the attitude or character of these boys because that is outstanding," Klopp said. "If we don't perform against United, it is because of other reasons.
"We lost at Burnley with 80 per cent possession, but there is 100 percent opportunity for us to win at United.
"Maybe a lot of people will think United are in a good run and Liverpool are not that good. But I think this is the best time to jump, so let's go."
Klopp and Co. head to Old Trafford after the two teams played out a goalless draw at Anfield in October.
United stifled Liverpool and manager Jose Mourinho was criticised for his defensive tactics on Merseyside.
Klopp knows he might have to adopt similar tactics away from home.
"We have different things to do," Klopp said. "Against Manchester United, we don't have to think about 80 percent possession because that will not happen. So, we have to think about different things.
"Even though we have improved in possession this season, we can still be a really good defensive and counter-attacking team.
"And that is a really good thing to know when we go to Old Trafford.
"We are really looking forward to it because we feel we can still cause problems with a well-organised formation."