There is plenty on the line in the 170th league encounter between these arch-rivals, who are separated by just two points in the race for second place.
The last four meetings have finished all square, but it is United who edge things overall with 67 wins to the Reds' 55, dating back to the first clash well over a century ago.
Follow all of the action as it unfolds with our extensive updates below.
MANCHESTER UNITED: De Gea; Valencia, Bailly, Smalling, Young; Matic, McTominay; Mata, Sanchez, Rashford; Lukaku
SUBS: Romero, Darmian, Lindelof, Shaw, Carrick, Fellaini, Lingard
LIVERPOOL: Karius; Alexander-Arnold, Van Dijk, Lovren, Robertson; Oxlade-Chamberlain, Can, Milner; Mane, Salah, Firmino
SUBS: Mignolet, Wijnaldum, Gomez, Henderson, Lallana, Solanke, Matip
The whistle sounds for full time, meaning that Manchester United hold a five-point advantage over Liverpool in the race for second place. Another huge home win for the Red Devils, hot on the heels of overcoming Chelsea here by the same scoreline, with Marcus Rashford's brace proving the difference in the end.
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90+6 min FULL TIME: MANCHESTER UNITED 2-1 LIVERPOOL
90+4 min McTominay sends the ball around the back for Lukaku to chase down, but Lovren got across to prevent the Belgian from charging through on goal. Still, that has eaten up a further minute or so and we are now in the dying embers.
90+2 min A collective gasp let out around Old Trafford as the fourth official holds up his board, indicating a further six minutes of time. Liverpool have created so very little in this second half; they must now launch the ball into the box.
90 min MANCHESTER UNITED SUB! Mourinho able to run down the clock by making his second change of the afternoon, bringing on Lingard for Mata. Antonio Valencia is cautioned for a high boot on Sadio Mane, catching his opponent close to the shoulder.
88 min The referee stops play due to matters boiling over a little. Solanke caught Smalling in the groin area and a couple of players came face-to-face - handbags, more than anything. Now just a couple of minutes of normal time left to play here.
86 min Mata's shot is blocked as United go in search of a third goal. Liverpool have not registered a shot since Bailly put into his own net to drag them back into the contest. Milner with a delivery into the box, which Valencia was there to clear.
84 min LIVERPOOL SUB! Dominic Solanke has been thrown on in place of Robertson, as Klopp goes all out for a goal. Prior to that, Wijnaldum - doubtful today due to a recent illness - replaced Alexander-Arnold. All three Liverpool changes made.
82 min Done Klopp a slight disservice there - it was Lovren he was having a pop at, not the officials. Young sends a free kick into the middle, slightly out of Marouane Fellaini's reach, with Karius able to get two big fists to the ball.
80 min Klopp absolutely furious with the officials after a decision goes against Lovren for his double foul on Fellaini. Craig Pawson having a few words with the German, reminding him that he cannot leave his technical area.
78 min Still technically have not had a shot on target for around 50 minutes or so now. Bailly's own goal has given third-placed Liverpool a real lifeline in this match, setting up the grandstand finale we were after at Old Trafford.
76 min Both managers with a huge part to play in the remainder of the contest. Fellaini and Lallana the players brought on for United and Liverpool respectively so far - who will be next to join them? Lallana's cross goes behind for the Reds' ninth corner.
74 min A little over 15 minutes left to go at Old Trafford and it is still very much all to play for. Liverpool seeing plenty of the ball since pulling a goal back, but United forming a brick wall to keep their opponents out. Can the hosts see things through?
72 min MANCHESTER UNITED SUB! Rashford makes way for Fellaini, as Mourinho shores up the middle of the pitch. A standing ovation for the Englishman, who as things stand will be the matchwinner in the 170th league meeting between these sides.
70 min How often do we see this? A team a couple of goals ahead and bossing a game, before conceding and then being left hanging on. United next exactly having to defend for their lives just yet, but we can expect Liverpool to go all-out attack now.
68 min Now then! The atmosphere around Old Trafford has completely changed with one swipe of Bailly's boot. Mane did well to find a yard out wide and swing the ball towards the front post, where Bailly was waiting to rather comically send the ball past De Gea. Think it came off the defender's calf in the end.
67 min GOAL! MANCHESTER UNITED 2-1 LIVERPOOL (ERIC BAILLY, OG)
66 min It has now been more than half an hour since the last shot on target from either side. Not been a classic Premier League affair, though this heavyweight fixture very rarely is these days. United fans will not care whatsoever, of course!
64 min Mourinho criticised for his tactics at Anfield in October but there can be no complaints this afternoon. Still 25 minutes to play but his side are cruising at the moment, with Liverpool not really showing any signs of scoring.
62 min LIVERPOOL SUB! Jurgen Klopp makes his first change of the afternoon, bringing on Adam Lallana for Alex Oxlade-Chamberlain in what is essentially a like-for-like change in midfield. Will fresh legs equal fresh impetus?
60 min Smalling pushes Salah to the ground and somehow gets away with it. This second half has been very scrappy and bereft of any chances, which will suit the home side - leading through two Rashford strikes - down to the ground.
58 min Liverpool starting to turn the screw a little now. It is all very scrappy but United are doing enough to keep Salah, Firmino and Mane quiet. Mourinho will not breathe easily unless his side net a third goal of the afternoon.
56 min United a tad fortunate for a second time in this second half as Robertson's cross hit Valencia's arm. Seen them given, though on this occasion the referee was probably right to let play continue. Still awaiting that United change.
54 min Mourinho looks the more likely of the two managers to blink first when it comes to a change, with that first alteration about to be made - Fellaini possibly to grab more control of midfield. Oxlade-Chamberlain's shot is blocked by Matic.
52 min Van Dijk sends a header on to the roof of the net after climbing highest to meet the corner. Young then had his hands all over Salah inside the box - had the Egyptian gone to ground the visitors may well have been awarded a penalty kick.
50 min Lallana among those to have been sent out to warm up by Klopp, so we could see a change shortly. United's gameplan working a treat at the moment, stifling Liverpool and looking very comfortable with their two-goal advantage.
48 min The visitors attempting to show a little more urgency from the off, but a dreadful pass from Oxlade-Chamberlain put paid to that. Klopp will likely make a change or two in the next 10 minutes if the game continues in this manner.
46 min RESTART! You have to go back to 1984 to find the last time Manchester United last a home league game at Old Trafford after taking a lead into half time. The odds very much stacked against Liverpool, who are unchanged for the second half.
Marcus Rashford's first-half brace has put Manchester United well on course to all three points as we reach the midway point at Old Trafford. Liverpool have no really turned up, getting in just a couple of tame shots from range, and now have it all to do in the second 45.
45+3 min HALF TIME: MANCHESTER UNITED 2-0 LIVERPOOL
45+1 min Lovren gets his head to the corner but cannot send it goalwards. Not too dissimilar to Van Dijk's miss earlier in the half, coming just a couple of minutes before Rashford's second goal of the contest to put the hosts in complete control.
44 min United need to remain focused now as we enter the final stages of the first half. Young with some solid defending to cut out the cross, with Salah finding himself in some space at the back post. The Egyptian forward has had a quiet first half.
42 minvMata may have missed the target from that big chance, but the home fans certainly appreciate the build-up play. Liverpool caught completely cold by their opponents this afternoon, though while it remains at just 2-0 this one is not quite over.
40 min CHANCE! Glorious chance for Mata to effectively kill off this contest. The Spaniard is picked out unmarked six yards from goal but, rather than controlling the ball and getting a shot away, he instead went for an overhead kick. Bad contact in the end, with the ball flying wide of the target.
38 min YELLOW CARD! A frustrated Oxlade-Chamberlain is cautioned for going through his man. Bailly initially does well but then ponders his next move for too long, allowing Firmino to pounce, but the Reds just unable to find that killer final pass at the moment.
36 min Less than 10 minutes to go until half time and United are in complete control of this match. That will all change if Liverpool can find a way through, but that does not look like happening on the basis of the opening 36 minutes.
34 min SAVE! Firmino with another straight shot from the edge of the box. This one had a little more conviction, but it will require a lot more than than for De Gea's net to be breached for just the seventh time here this season.
32 min SAVE! Technically a first save of the afternoon for De Gea to make, but he barely had to break stride to keep out Firmino's shot from the edge of the box. The Reds in desperate need of some inspiration here after a slow start.
30 min YELLOW CARD! Half an hour in and Rashford now has a yellow card to go with his couple of goals. The forward slid in on Milner, giving away a free kick that the Reds could not convert from. United then clear away from the corner.
28 min Good cross into the middle of the United box is cut out before a player in white could convert. I said 10 minutes ago Klopp will not be too concerned; maybe he will be now, as Rashford has given United some breathing space at Old Trafford.
26 min Many have questioned why Rashford has not started more games this season - the opening 26 minutes have done little to quiet those queries. Yet another brilliantly composed finish from the Englishman, tucking home a loose ball after Lukaku's through-ball was cut out. Two chances, two goals - game over?
25 min GOAL! MANCHESTER UNITED 2-0 LIVERPOOL (MARCUS RASHFORD)
24 min CHANCE! Good defending from Valencia to cut out a pass intended for Firmino around the back. From the resulting corner, Van Dijk fails to find the target from five yards. Under pressure from Matic, he could only meet the cross with his shoulder and not his head.
22 min A quarter of the way through what has been a quiet contest, with Rashford's well-taken strike 14 minutes in proving to be the only piece of quality thus far. Klopp will not be too concerned at the moment; still plenty of time to turn things around.
20 min Man United have taken the lead in 352 previous home games and lost just three of them, most recently to Liverpool. Still just the one shot of any sort at Old Trafford this afternoon, leading to the game's breakthrough goal.
18 min Firmino does well to keep the ball in play when many had fallen asleep. The Brazilian sent a decent delivery into the box, too, with the ball inches above the head of Mane at the back post. Up the other end, Robertson gets across to deny Rashford.
16 min That was the first shot of any sort in that match, with the finish belying the quality of the contest up until that point. Alexander-Arnold should have done better, being bullied by Rashford after finding himself slightly out of position.
14 min What a finish from Marcus Rashford! The Englishman may have been frustrated by a lack of minutes over the past couple of months, but there is no way Mourinho can leave him out on the basis of this goal. Lukaku with the flick-on, allowing Rashford to nod the ball forward, before cutting inside on his right and bending it out of Karius's reach - goal number five of the Premier League campaign.
13 min GOAL! MANCHESTER UNITED 1-0 LIVERPOOL (MARCUS RASHFORD)
11 min Rashford unlucky after getting to the ball first but failing to keep it in play. Both sides struggling to really keep a hold of the ball so far, but in many ways that is what many expected due to the tension that comes with this fixture.
9 min Firmino attempts to find Mane through the middle when he had Salah breaking down the right - bad choice. Looking at the possession stats, the visitors have seen three-quarters of the ball in the early stages here, which is quite surprising.
7 min Not a lot to report back on in the opening seven minutes of the contest. Liverpool had a turn bossing possession and now United are doing likewise, with neither side able to really get the ball into the final third of the field.
5 min That game has yet to really settle down, but that was to be expected in a fixture of this magnitude. Liverpool now being allowed to knock the ball around just inside the United half; the big question is whether they can feed Salah, Firmino and Mane.
3 min Sanchez attempts to close down Liverpool's centre-backs but soon realises he is on his own in doing so. The Chilean then appeared to ask his teammates whether they were going to push up high or allow the Reds to pass it around - strange.
1 min KICKOFF! Great atmosphere inside Old Trafford for this 170th league meeting between Manchester United and Liverpool. In case you were unaware, these two teams quite simply do not like each other! What an afternoon we are in store for.