David Moyes wrote a letter last week to season-ticket holders at Old Trafford thanking them for their support. It’s easy to understand why he felt that was justified. While there have been growing murmurings of discontent, it is hard to imagine supporters of many other clubs being so forgiving of a manger who has led their team to a decline of 23 points in just one season.

Whatever the reasons for it -- at times it comes off as simply a continuation of the defiant, siege mentality of the Ferguson years -- it has prevented Moyes’s reign from being plunged into deeper crisis. But were Manchester United to lose to their fiercest rivals on Sunday, even the staunchest Moyes loyalist may begin to voice discontent.

At the same stage of last season, Manchester United held a 29 point advantage on Liverpool in the Premier League table; the two teams were not even competing in the same realm. When they meet on Sunday, Liverpool will have the chance to move 14 points clear of United.

Sir Alex Ferguson famously said that his greatest challenge during his time at Old Trafford was to knock Liverpool off their perch. It was something he achieved spectacularly. United finished above their North West foes for 21 straight seasons. Now, once again the two teams appear to be heading in very different directions. In Liverpool, United have the perfect warning of how quickly an all-conquering club can be mired in years of relative mediocrity.

Moyes is, of course far from the sole cause of United’s decline and is, indeed also a symptom of it. Like Liverpool when they fell from their perch in the 1990s, United have failed to invest in players of requisite quality to continue their success. And, like failed Liverpool managers Graeme Souness and Roy Evans, Moyes is also example of a club looking inward rather than widening their net and embracing the modern age.

It’s hard not to think that Ferguson hand-picked Moyes because he is a man cut in his own image -- a tough, determined Scot from Glasgow. It’s also true that Ferguson, like Moyes wasn’t exactly a tactical revolutionary. However, why Ferguson was able to succeed for so long was because he continued to embrace new ideas from outside. Steve McClaren, Carlos Queiroz and Rene Meulensteen were hugely influential figures behind the scenes in three different periods of success. One of Moyes’s first decisions, and arguably his first blunder, was ignoring Ferguson’s advice and dispensing with the current coaching staff -- including Meulensteen -- in order to bring in his own trusted lieutenants as well as a current and former United player with no coaching experience.

For much of the season, Moyes’ United team have been an unimaginative relic. His focus on straight lines and getting the ball out wide before hitting it into the box not only looks horribly outdated but fails to get the best out of the not inconsiderable talent at his disposal. Robin van Persie’s body language and contribution -- if not his words -- are a perfect illustration.

While Manchester United have been insipidly stale, Liverpool have been anything but. Unlike Moyes, Brendan Rodgers has a proactive philosophy of how he wants his teams to play. His desire for a possession-based game with keen pressing has been evident throughout his managerial career. Yet, what has arguably been most admirable about Rodgers’s work this season has been his ability to adapt.

Luis Suarez is one of the best players in the world and one that any coach would relish working with, yet you suspect that he doesn’t exactly fit snugly into Rodgers’s ideal vision. Certainly, having two players as lethal as Suarez and Daniel Sturridge has provided Rodgers with an, admittedly wonderful, conundrum.

In trying to get the best out of the duo while also maintaining a balance to his team Rodgers has tried many different systems. And he hasn’t always got it right. Notably in the first halves of matches against Arsenal and Aston Villa, his team were overrun in key areas. Liverpool can still look worryingly open, but Rodgers is getting the best out of his best players and has made them the most entertaining team to watch in the Premier League.

It’s arguable that Liverpool’s finest performances have come with Rodgers abandoning his stylistic beliefs. In the past his teams often played neat football but were often rather blunt. Instead, against Tottenham, Everton and Arsenal, Liverpool hit their opponents fast and hard in transition. When hammering Everton and Arsenal, Rodgers was happy to have his side cede the possession battle.

At their best, Liverpool have also prospered from devastatingly quick starts. Were the Reds to come firing out of the traps at Old Trafford the way they did when going 4-0 up in 20 minutes against Arsenal, then they could rip through a United team that has been desperately lackluster in recent weeks.

It is also true that Liverpool have been far more effective at home this season and going to Old Trafford, their fate could depend much on their mentality. With a midfield that lacks a commanding presence and a defense that has been less than secure, United could be ripe for the taking.

One of Moyes’s biggest selection dilemmas is whether to reinstate Nemanja Vidic to the heart of the defense or keep faith with the partnership of Chris Smalling and Phil Jones that kept a clean sheet last time out at West Brom. While Vidic’s experience could be crucial in a fierce derby match, his lack of pace will leave him extremely vulnerable against the pace and movement of Suarez, Sturridge and Raheem Sterling.

Regardless, the fact is that Liverpool are just a better team right now. And, while United lack the dynamism to exploit Liverpool’s weaknesses, the Merseysiders have more than enough to expose those of their opponents.

Prediction: Manchester United 1-2 Liverpool

Team News

Manchester United:
Nani has returned to training for the first time since suffering a hamstring injury in early December. In his pre-match press conference, Moyes also confirmed that Rafael, Jonny Evans and Javier Hernandez are all in contention to be involved on Sunday.

Liverpool: Rodgers has also been handed some positive news with center-back Mamadou Sakho and defensive midfielder Lucas Leiva returning to the squad. Jose Enrique is now Liverpool’s only absentee.