Liverpool's season continues to deteriorate week-by-week, and it lurched even lower on Sunday when they fell to a crushing 3-0 defeat at the hands of Manchester United at Old Trafford.

Having gone out of the UEFA Champions League on Tuesday night, the loss at United had shades of the reverse fixture back in March - where Brendan Rodgers' side romped to an emphatic win. This time around, there were no such happy memories to be taken as the Reds were made to rue missed chances.

Louis Van Gaal's side were clinical and were on hand to take advantage as Liverpool's Raheem Sterling missed a glorious opportunity. After Adam Lallana's terrific through ball into the six-yard box, David De Gea prevented Sterling's weak close-range effort with ease and 25 seconds later, Wayne Rooney placed the ball beyond the deputising Brad Jones from 20-yards after a mix of lazy man-marking and poor positioning allowed the Red Devils to snatch a 1-0 lead. 

The visitors did not concede defeat after enjoying the better of the opening half-an-hour, but Van Gaal's side soon doubled their lead. Shortly before half-time, it was a two-goal lead as Juan Mata took advantage of debatable decision-making to head home. Ashley Young's cross was flicked towards the Spaniard at the back post, and all he had to do was connect with the cross to score. 

At half-time, the Reds attempted to hit back by bringing Mario Balotelli on after Sterling had wasted plenty of chances. De Gea was on hand to make a number of impressive stops, keeping out the Italian and the 20-year-old English winger and Robin Van Persie made it an even worse afternoon for Brendan Rodgers' side.

Kolo Toure left plenty of space in front of goal after an ambitious run upfield and when Wayne Rooney's cross failed to find his teammate at the back post, Dejan Lovren failed to make an adequate clearance. The Croatian's attempt fell straight to Juan Mata, who teed up a shot and enticed Brad Jones out of his goal, until he rolled it across the box to Van Persie who only had to place it into an empty net to make it 3-0, which it finished.

Liverpool arguably could have taken at least one point, or even three, but the same old mistakes ultimately let them down. Defensively, all three goals were down to mistakes - the first from Alberto Moreno being out of position and Jordan Henderson failing to track his man, the second down to bo-one marking Mata at the back post and the third, Dejan Lovren and Brad Jones' individual errors. In the final third, Sterling made it all too easy for De Gea to make a string of, it has to be said, top saves. Balotelli made somewhat of an impact and was very unlucky not to have got his first league goal for the club as De Gea made a truly world-class save to prevent his powerful effort finding the roof of the net. 

In the end, it was a very disappointing result for Liverpool and Brendan Rodgers', who saw his side lose their 7th league game of the season after just 16 fixtures, and here are five things we learned from Manchester United 3-0 Liverpool:

1. Brendan Rodgers is in real trouble.

After each negative result, the next game always seemed to be billed as a turning point for Liverpool's season. The back-to-back wins over Stoke City and Leicester City proved to be a false dawn, as they struggled to overcome struggling Sunderland at Anfield, before abject displays against FC Basel and now Manchester United in the space of a few days. Things are becoming dangerously bleak for Liverpool, as the dark clouds that surrounded Roy Hodgson's tenure at Anfield seem to gather. The Reds are seven points out of touch with fourth place, two games away from the half-way point in the Premier League season, and even with Daniel Sturridge hopefully set to return in the coming weeks, it's hard to find much inspiration to hope things will improve. He seems to have tried every tactical possibility, but none are going his way. Though there are plenty of ways he could make it easier for himself - returning to the diamond shape, not ignoring the likes of Emre Can and keeping his delusional post-match comments to a minimum - it is hard not to feel a bit sorry for the Northern Irishman who was a slip away from going into the Liverpool folklore. Nevertheless, he is in real trouble. The knives are sharpening and there's a real sense amongst the crowd at Anfield that he is a dead man walking. The once fervent support for him is waning, and potential candidates are already being lined up to succeed his throne. How different it all could have been, but the Liverpool fans are growing weary of the constant mediocrity they are seeing from their side - who cannot defend, attack or doing anything resembling the sensational style they flaunted so brilliantly last season. Their swashbuckling identity is back, and despite all the "positive signs" that were shown as the Reds at least created a number of strong opportunities, it is a results-driven business and the longer results fail to go their way, the likelier that Rodgers will be on the unemployment list sometime within the coming months.

2. A top goalkeeper makes the world of difference.

In a day that Liverpool's first-choice number one was dropped "indefinitely" for a keeper that has made nine Premier League appearances in four years for one side, it was the goalkeeper on the opposing side that had a huge say in the game, proving that the last line of defence is crucial to competing in the top level of English football. For months, Simon Mignolet has struggled for form, making error after error, with little to no competition for his place between the sticks. Now, it has got to the point where Mignolet just cannot warrant a starting spot with such form, but Jones offered little restbite. The experienced Aussie was poor and the difference between his performance and that of David De Gea in the goal up the other end of the pitch, was staggering. The Spaniard produced a phenomenal performance, making some key saves to keep a clean sheet and help his side to the victory. Without his save early on, Raheem Sterling and Liverpool could have taken something drastically different away from Old Trafford on Sunday - but De Gea sprawled well to save the admittedly weak close effort from the 20-year-old. The hashtag #ThingsDavidDeGeaCouldSave didn't begin trending for nothing. With his contract situation known to be up in arms, Louis Van Gaal would do well to tie him down to a lucrative long-term contract, as this isn't the first-time season he seems to have single-handedly had his say in the outcome. He produced five saves and deservedly took Man of the Match, having earlier produced similar performances against Everton and others. Jones, meanwhile, will keep his starting spot in the coming weeks - as per Brendan Rodgers' word after the full-time whistle. He was not wholly convincing and after early season rumours seemed to indicate the Reds would look to take Victor Valdes on a costless, their goalkeeping situation is one that must be addressed in January if they are to prevent the defensive rot. 

3. Liverpool need more striking options.

What was abundantly clear at Old Trafford, was that whilst Liverpool were wasteful, United were clinical. The goals that flew in from here, there and everywhere last season have dried up - without their striking duo of SAS, and the other strikers in the reserves are not up to standard. The politics behind the disappearance of Fabio Borini are difficult to explain, but it seems that the powers that be are intent on demonstrating to the Italian that he is no longer welcome. Rodgers' first ever signing as manager, costing £12 million, has failed to even feature in the matchday 18 in recent weeks - despite the obvious need for extra firepower, which suggests that the 23-year-old who turned down moves to Sunderland and Queens Park Rangers in the summer is slowly being pushed out. Rickie Lambert, despite a valiant effort in filling in when Mario Balotelli was out with a groin injury, cannot be consistently relied on. His short-term impact was good, as he added two goals in two games, but he quickly grew tired with the number of successive starts and his impact deteriorated subsequently. The 32-year-old is a viable option when the squad needs rotating, but he's hardly the man to rely week-in, week-out on. Balotelli, meanwhile, has had a trouble career on Merseyside so far. The gamble that Rodgers talked about has backfired, and the consequences are startling. After transfer windows where the likes of Diego Costa and Alexis Sanchez were forward targets, the Italian was chosen over Samuel Eto'o in the final days of the market and despite a few signs that Balotelli has the talent to make a name for himself positively, he has been mis-managed. Played alone when crying out for a striking partner has not seen the Reds get the best out of him, whether it be a deliberate ploy by Rodgers to tempt FSG into giving him more funds, or simply the lack of awareness of what Balotelli needs - the 24-year-old has yet to even get a league goal, his only strikes in red coming against Ludogorets Razgrad in Europe and Swansea City in the Capital One Cup. Liverpool can't afford for this to continue, even when Sturridge returns. More attacking options are a necessity considering the Englishman's injury prone nature. Be it Paulo Dybala, Alexandre Lacazette or another name - the Reds need to pay big bucks for a man they can rely on to add goals, or else the top four will be a few more years wait away once more.

4. Lucas Leiva is essential.

Brought in under Rafael Benitez, Lucas Leiva's time at Anfield has taken every up and down. From being booed off by the home supporters to establishing himself as a future vice-captain candidate, to twice rupturing his Anterior Cruciate Ligament to his re-emergence in the last few weeks - he's seen it all. A few years ago, he was seen as one of the best defensive midfielders in the game. Quite a feat, given that he initially came to England as an attacking midfielder from Gremio. But injuries soon cast him into months and months on the sidelines. Under Rodgers, he's never really come to the fore - with Steven Gerrard stealing the spotlight after being reinvented into a defensive anchor position last season. Now, however, it's becoming more and more obvious (at least to the fans) that Lucas is the man to field if defensive security is a must. Rodgers has finally realised that it should be Lucas and not Steven Gerrard marshalling the Reds' defence, and Lucas' return to the starting line-up has coincided with them keeping two clean sheets in three games - but he was dropped on Sunday. Seemingly due to Gerrard's ability to rise the occasion, as seen in mid-week, the captain was preferred in the defensive midfield role and the results were hardly surprising. The 34-year-old looked jaded and was almost non-existent in his side's poor defensive performance. Trusted with protecting the back-four, he did anything but. Even his set-piece delivery was off the mark, as it has been throughout 2014-15. It is obvious Liverpool need to maintain solidity from the back, particularly if they are to continue playing out from the defence and from recent displays, the answer is that Lucas is the best player suited to the defensive midfield position in the current Liverpool squad, because it feels more natural and he has the physicality to match up against the Premier League sides. Gerrard may not like it, but it's the best for the Reds. Lucas has to start in front of the defence if they want to keep clean sheets, and ultimately, win games - for the timebeing, at least.

5. Raheem Sterling struggling with the pressure.

When times are hard, it is often seen in football that the onus is on the best player to drag the side through the mud - whoever it may be. Five or more years ago, it was Steven Gerrard's task and more lately, Luis Suarez was the one who had to set the standards. With one of those now residing on the sunnier shores of Barcelona and the other having lost the ability to single-handedly win games, it has fallen to Raheem Sterling to step up the plate. Last season, he shone in tandem with Suarez and Daniel Sturridge, creating a formidable attacking trio that's pace and trickery frightened any defence. After burning out in his first campaign, the 2013-14 season really establish Sterling as one of the most promising young attacking talents in Europe. His reputation looked only set to grow and grow early into the season, as he added a number of goals and assists - but he soon hit a stumbling block. Suddenly, he wasn't as willing to take on his man. He couldn't outmuscle the opposition or burst down the wing as if no-one was there. Everything that made Sterling tick seemed to evaporated. Allegations that he was tired after his role in the World Cup for England and only a few weeks rest before pre-season and the Premier League campaign were rife in the media, particularly after he sat an international game in October. Then, at Leicester City - he looked to have gotten over it. The best of Sterling was back, as he helped himself to a splendid assist and a virtuoso performance at the King Power Stadium. Was this it? Was Sterling returning to the form that could help trigger his side's attacking exploits? Sadly not. Given Rodgers' and Liverpool's over-reliance on the 20-year-old, whose age it is difficult to forget when sometimes watching him, he is struggling. Despite such age, he is coming under for much harsher criticism than when his performances cooled off in the first season. With his contract talks ongoing and the supposed lust for more money being touted about the back pages with Liverpool's stuttering form, the big sharks of Spain and even England will be smelling blood. No doubt about it, Sterling is a terrific talent, even if he has been inconsistent so far this season. With the right rest afforded to him, and the right players surrounding him, the Jamaican-born youngster would be sure to pose a threat to any defence. It's vital that Liverpool ensure they keep a hold of him, but they also cannot afford to over-rely on him, yet they can rarely afford to drop him. The last time that happened, Rodgers' side put in one of their worst performances yet in the final third, a dull 1-0 home loss to Aston Villa. It's a tough situation and one that has to managed very well by the Ulsterman, who has plenty of other things on his mind.