The Old Trafford clash is shaping up as the pivotal match of the season as both clubs eye the Premier League title having made it through to the last eight of the Champions League this week.
Their intense rivalry is due in part to the fact that their city rivals Everton and Manchester City have rarely challenged for major honours over the last decade, increasing the pressure on Liverpool and United to assert their authority over each other.
If the Liverpool side that demolished Real Madrid 4-0 at Anfield on Tuesday comes out with all guns blazing and wins at Old Trafford then their title challenge will be back on.
But if they produce one of the pedestrian displays that have cost them vital points against lesser opposition in the last few months, they will fail to take all three points and their title dreams will be over.
United, though, also go into the match on a high following their 2-0 win over Inter Milan at Old Trafford on Wednesday. They have won their last 11 league matches and been playing consistently well, in stark contrast to erratic Liverpool.
Rafa Benitez's side led the table from the end of November until the middle of January when United went top and it still seems inconceivable after their awesome display on Tuesday that the same Liverpool players are capable of producing such uninspiring performances in the league.
Like United, Liverpool have lost only two league matches all season, but they have drawn 10 -- twice as many as United -- and now trail them by seven points having played one more match and are third, behind Chelsea on goal difference.
WINNING DOUBLE
However, Benitez believes his side can complete what would be a remarkable winning double by beating United to maintain their interest in the title race.
After beating Real, he told reporters: "We have an important game next, but we have played well here, scored four goals and are very confident. That is the best way to prepare for such a game.
"It was important for us to play that well, but we are now facing a very good team and we must win to close the gap at the top."
Chelsea have rediscovered their form under Dutch coach Guus Hiddink and will be full of confidence after their aggregate victory over Juventus in the Champions League on Tuesday when they play Manchester City at Stamford Bridge on Sunday.
Aston Villa, without a win in six matches but hanging on to fourth place ahead of an Arsenal side who have clicked back into form, face a Tottenham Hotspur team still not safe from relegation despite being in 12th.
