What you could either call passion or poison makes this perhaps the spiciest high-profile fixture in the English calendar, and it is given an extra frisson when it actually means something in terms of the wider competition.
United's social media team were certainly excited about Sunday's clash at Old Trafford this week. Either that or a 10-year-old child had hacked their Twitter account:
It was at its best when both sides were fighting for the title, but while this season that isn't the case, the clash has taken on an entirely different dynamic.
For 20 years, Manchester United were dominant in the league, with Liverpool providing brief genuine threat for the title on a couple of occasions. Even if Liverpool won specific battles, there was a permanent and inevitable sense that United would eventually win the war.
Only once in the Premier League era have Liverpool finished above United, a 5-0 win over Ipswich on the final day of the 2001/2 season securing second place behind Arsenal, as United slipped to third.
This time though, they are almost certain to beat their rivals in the table. They are second, 11 points clear of United back in sixth with 10 games remaining. It would take something akin to a miracle for David Moyes' side to overhaul such a gap, and it represents a changing dynamic in this rivalry.
For the first time in a couple of decades, Liverpool are demonstrably a better side, with their attacking quartet of Luis Suarez, Daniel Sturridge, Raheem Sterling and Phillippe Coutinho leading them to a remarkable 73 goals so far this term, already more than all-but two teams (United and Chelsea) managed in the whole of last season.
Liverpool will go into this game expecting to win, something that still seems remarkable for a visiting side to Old Trafford, but they will be justifiably confident, given their recent form. They are unbeaten in the last nine, having won seven of those games and scored 29 goals in the process.
Brendan Rodgers said this week that his players are certainly up for it—indeed, his job seems to have been to temper their enthusiasm, rather than try and inspire it.
He told talkSPORT:
It was interesting really as we had an adaptation day after they had been off for a few days. It was supposed to be a low intensity session, but the quality and the intensity they worked at was incredible. I actually had to take them off it a little bit...
We have been terrific for the last 14 months or so and the club is on a real high. That's big credit to the players and all the staff, who are working tirelessly every day.
Sunday is a game we are really looking forward to. For us it's about retaining the focus. We know it's a big game but we've done well in a lot of the big games this season.
This is not just a game about rivalry for Liverpool. If they can win at Old Trafford, then their superiority over their adversaries will be confirmed, and will be a significant blow and message to the rest in their title challenge.
It's been a long time that, of the two teams in this fixture, we've been able to say that about Liverpool, rather than United.