Klopp: 'Results machine' Man Utd are in Premier League title race
United sit third in the table, 11 points behind leaders Arsenal but with a game in hand.
Ten Hag's side have already ended a six-year wait for silverware by lifting the League Cup last weekend and remain in the hunt for more trophies in the FA Cup and Europa League.
"It is obviously not a team built up for the next 20 years because of the players they have signed. It is for now - but now they are really good," Klopp said at his pre-match press conference on Friday.
"They have turned into a results machine. They are squeezing results out with some really good performances. Top football, and if it is not going so well, they still get results.
"That's why they are there. Everyone knows it, they are fully in a fight to win the league."
Marcus Rashford's career-best tally of 25 goals in all competitions has been a major factor in United's resurgence.
The England international scored just five times last season and Klopp reserved special praise for the 25-year-old, whom he has previously lauded for his efforts in campaigning to end child food poverty.
"It's pretty much impossible to be happy about something positive at Manchester United when you are the Liverpool manager but I am really happy for Rashford because he had a very difficult last year where he was not performing on the level that he is able to perform.
"Now he is playing incredible. His speed, his technique - it is a mix of everything. How calm he is in front of goal, he scores worldies, he scores the simple ones, he can put his head in. All these kinds of things.
"We have to defend against that collectively. He is not their only world-class player."
United were hammered 5-0 at home and 4-0 away in their two league meetings with Liverpool last season.
Form slump
But the tables have turned as Klopp's men have suffered an incredible slump in form.
Liverpool are 10 points behind United in sixth and face a huge fight just to qualify for next season's Champions League via a top-four finish.
Real Madrid laid bare the Reds' deficiencies when embarrassing them 5-2 last week -- the first time Liverpool had conceded five goals at home in European competition.
However, there have been signs of recovery in the Premier League, with Liverpool taking 10 points from a possible 12 thanks to four consecutive clean sheets.
"This is a week where I would like to give the season a proper push," said Klopp.
"I said I would like to squeeze everything out of this season. That means to finish as high as we somehow can, but nobody knows where that will be. So we just have to make the next decisive step and we go from there."
