Liverpool's quest for a quadruple is alive and well after they came through their toughest week of the season with everything still up for grabs.
A 2-2 draw at Manchester City kept their Premier League title bid on track and after seeing off Benfica in the quarter-finals of the Champions League, the Reds produced a superb first-half display to beat City 3-2 in the semi-finals of the FA Cup on Saturday.
With Pep Guardiola's men not playing Brighton until Wednesday night, Liverpool can go top of the table - for 24 hours at least - with victory over City's neighbours United on Tuesday evening.
When: Tuesday, April 19, 20:00 BST
Where: Anfield, Liverpool
How to watch: Sky Sports Main Event
Who is the ref for Liverpool vs Man Utd
Martin Atkinson is the man in the middle at Anfield.
The Yorkshire official last took charge of Liverpool in their 2-1 FA Cup win over Norwich, booking Jordan Henderson and Diogo Jota and three Canaries players.
The last time he was assigned to a United game, he booked just one player, Scott McTominay, in their 3-2 win over Arsenal back in early December.
Season stats 2021/22: All matches (23), yellows (60), reds (3), penalties (7)
Liverpool had won 10 straight Premier League games before they drew 2-2 with Manchester City last weekend.
It's that run of form that gives them hope of making this season the best in their illustrious history.
Technically, they've only won one of their last three but that rather masks the wider picture.
The first was a battling 2-2 at the Etihad and the second a 3-3 draw with a weakened team against Benfica when the tie was already wrapped up.
Liverpool played some superb stuff in the first half at Wembley so they've proved they're capable of raising their levels when it really counts.
Manchester United had just one win in seven games before beating Norwich 3-2 on Saturday.
And, even then, it needed Cristiano Ronaldo to complete his hat-trick to get them over the line after the Canaries had fought back from 2-0 down.
United are still in the race for the top four but that's just as much down to the slip-ups of Arsenal and Spurs than it is their own performances.
Liverpool and Man Utd players in form
It's been quite a year for Sadio Mane after his winning penalty helped Senegal land the Africa Cup of Nations and he's hitting his best form again at a crucial time.
The Reds frontman scored away in Benfica, netted the equaliser at the Etihad and then scored two very contrasting goals in the 3-2 Wembley win on Saturday.
His tally for the season now sits at 18.
Ibrahima Konate has headed three goals in his last three games and is a huge danger from set-pieces, while midfielder Thiago Alcantara's undoubted class is really proving to be the difference in the heart of this Liverpool side.
For United, Ronaldo's treble against Norwich took him to 15 Premier League goals this season.
That makes him the third highest scorer in the Premier League along with Jota.
It's hard to pick out another United name.
Last three meetings
Man Utd 0-5 Liverpool (October 24, 2021)
Liverpool produced an astonishing display to blast Manchester United 5-0 and record their biggest ever away win at Old Trafford.
The rampant visitors were 4-0 up at the break thanks to an early strike from Naby Keita, a second from Jota and a Salah brace.
With the hosts still in shock, Salah added a brilliant fifth in the 50th minute after being played through by Henderson and dinking over David De Gea.
Paul Pogba was sent off on the hour after a two-footed lunge on Keita and United were grateful that Liverpool decided to play out time after that.
Man Utd 2-4 Liverpool (May 13, 2021)
It looked grim for Liverpool after 10 minutes. Klopp had never won in six previous trips to Old Trafford and they found themselves 1-0 down after an early strike from Bruno Fernandes.
But needing to win to boost their hopes of pinching a Champions League spot, the Reds fought back to complete a deserved 4-2 win.
Jota levelled after half an hour before Roberto Firmino struck a double either side of the break (45' & 49') to give Liverpool breathing space.
Marcus Rashford cut the deficit halfway through the second half to set up a tense finish, but Mo Salah secured three huge points for the visitors with a breakaway strike in the final minute.
Man Utd 3-2 Liverpool (January 24, 2021)
A week after they'd played out a 0-0 stalemate in the league at Anfield, this FA Cup clash was a far more entertaining encounter.
Salah scored his first goal at Old Trafford to give Liverpool the lead inside 20 minutes before Mason Greenwood (26') and Rashford (48') swung the tie in United's favour.
Salah levelled just before the hour mark with his second of the game but the hosts struck the decisive blow when second-half substitute Fernandes blasted home an excellent 78th-minute free-kick to send United through.
Past 10 meetings
Liverpool wins: 4
Man Utd wins: 2
Liverpool scored: 18
Man Utd scored: 9
Ahead of the clash, Manchester United boss Ralf Rangnick labelled Liverpool an "extremely good" side.
"They are good, they're extremely good," Rangnick said of Liverpool. "It's no coincidence that they're as good as they are.
"Jurgen has built that team in the last six and a half years.
"Six or seven of those players used to be my/our players when we signed them for our clubs when nobody knew them."
Liverpool boss Jurgen Klopp made no attempt to play down the size of the clash, labelling it a game between "two of the biggest clubs in the world".
"It's a big game, a massive game, two of the biggest clubs in the world. Always we have to learn to deal with it. Some players had to learn how to deal with it. This time it's an incredible important game again for both teams.
"We have had to learn to deal with playing Manchester United. Some players had to learn how to deal with it. This time it's an incredibly important game again for both teams. That says it all. Both teams are fighting.
"The Manchester United we will face, they will go for it. They want to go to the Champions League. It will be an intense 90 minutes. We have to make sure they don't take our points to get there."
Predicted Liverpool vs Man Utd teams
Klopp has to juggle his team selections with the matches coming thick and fast for Liverpool, but thankfully he has the squad to do it.
Firmino and Jota only had five minutes each at Wembley so will be fresh for this test, although Liverpool's next game isn't until Sunday's Merseyside derby, so Salah and Mane may get the nod again.
At the back, there could be a return of Joel Matip, with Klopp happy to rotate him with Konate as Virgil van Dijk's partner.
Skipper Henderson is also likely to return after coming off the bench in the FA Cup semi-final.
Possible Liverpool starting line-up: Alisson, Alexander-Arnold, Robertson, Van Dijk, Matip, Henderson, Fabinho, Thiago, Mane, Jota, Salah.
Manchester United didn't start with a defensive midfielder against Norwich and left spaces through the middle.
They surely won't risk that against Liverpool after their 5-0 embarassment last time, although Fred and Scott McTominay remain injured. Nemanja Matic is likely to step in.
United could also be boosted by the return of Raphael Varane in the heart of their defence.
Possible Man Utd starting line-up: De Gea, Wan-Bissaka, Lindelof, Maguire, Telles, Matic, Pogba, Elanga, Fernandes, Sancho, Ronaldo.
Liverpool vs Man Utd prediction
The first meeting between the pair was embarrassingly one-sided although that was in the Ole Gunnar Solskjaer days.
Rangnick will likely shore things up a little but United have had some limp displays on the road and everything is going Liverpool's way at the moment.
The hosts have won every Premier League home game since the calendar turned to 2022 and they can keep that record going.
Take Liverpool to assert their dominance with a 3-1 win.