Jurgen Klopp urged Liverpool to fight for the "most important three points in your life" against Manchester United as the Reds aim to reach the Premier League summit.
Liverpool would, at least briefly, leapfrog Premier League leaders Manchester City with a draw at Anfield on Tuesday; Pep Guardiola's side are in action the next day against Brighton and Hove Albion.
Victory over United would move Klopp's side two points clear of reigning champions City, who suffered a 3-2 FA Cup semi-final defeat to Liverpool on Saturday to end their treble hopes.
United, meanwhile, have struggled once again this season and limped to a 3-2 victory over Norwich City last game, thanks to a Cristiano Ronaldo hat-trick.
While uncertainty surrounds Old Trafford, with Ajax coach Erik ten Hag widely expected to be named the next permanent United manager, Klopp warned his side of the dangers Ralf Rangnick's visitors will pose.
"We have to be angry in a good way, greedy, all these kind of things, like you are if you have won nothing and would be with nil points and it's the most important three points in your life," said Klopp.
"That's the attitude we need for this game. If we let United do [what they want] they will cause us massive problems.
"We have to be in the right mood, the people have to be in the right mood to really be ready to fight for the three points and not want to show we are in a better moment than United. Who is interested about that?
"There are times when you have better moments than other teams then you get a knock and that's it with the better moment. Who cares?
"They want the three points we need. That's that attitude we have to show."
A 5-0 hammering by Liverpool at Old Trafford in the reverse fixture in October contributed to United legend Ole Gunnar Solskjaer being dismissed the following month, with Rangnick placed in interim charge.
Rangnick has been unable to significantly alter the fortunes of United, but thanks to slip-ups by Tottenham and Arsenal, the Red Devils sit just three points behind the Champions League qualification spots.
Klopp sympathises with his fellow German as he suggested there are no short-term solutions for major clubs.
"We had a similar situation when I started here," Klopp said. "We were not flying from the first day, let me say it like this, and you might have thought after six or seven weeks: 'Is it really much better than before?'
"When you are in that situation, you just accept that you need all the steps. You cannot just put on a magic sprinkle and go from there.
"It is completely normal that expectations are always short-term, never long-term. You want the advantage now and forever, and not from five months on and forever. That is the problem we all have.
"That might be the situation there. But we don't face the team that has problems, we face Manchester United. The goalkeeper is world class, the last line absolute top, then [in midfield] I'm not sure if [Scott] McTominay and Fred can play and it might be [Paul] Pogba and [Nemanja] Matic.
"Then up front you can choose from [Jadon] Sancho, [Bruno] Fernandes, [Anthony] Elanga or [Marcus] Rashford. That's what we have to prepare for, not what happened last week."