Tim Krul, left, and Ayoze Perez walk off the pitch after Newcastle were humiliated by league leaders Manchester City.
He bagged another pair before being substituted in the 66th minute, while the in-form Kevin De Bruyne was also on target as Newcastle went bottom.
United swept to five wins in its six September fixtures in all competitions and came from behind to edge Wolfsburg in the Champions League on Wednesday.
United seemingly took a welcome step forward against Chelsea last weekend, but the team undoubtedly took two or more steps back in the second half against Manchester City yesterday. Two, if the club want to sack me they have to sack me because I am not running away from my responsibility or my team and from my conviction. Jamie Vardy scored his seventh goal of the season to give Leicester lead in the 28th minute, then Jeffery Schlupp doubled the lead in the 47th minute, before Dieumerci Mbokani pulled one back for the hosts.
That is the verdict of head coach Steve McClaren, who oversaw a 6-1 defeat at Manchester City despite leading for 30 minutes at the Etihad Stadium.
De Bruyne released him a minute later to complete an eight-minute treble with a delicate, dinked finish and the Belgium worldwide scored for the third top-flight match in succession when he swivelled to send an acrobatic near-post volley from Navas’ right-wing cross over Krul.
Aguero’s striking masterclass began just before the interval, hauling City back into a game in which they were struggling to subdue Newcastle, and continuing with renewed and devastating force after the break. It was becoming a real concern for Manuel Pellegrini that his principal goalscorer had just one goal from open play and looked well below par, bereft of his usual pace and dynamism.
There were victories for two of the surprise packages of the early season: Crystal Palace and Leicester.
And again!! De Bruyne to Aguero, who slid in front of his mark to score from close range. However even three goals wasn’t enough, as Aguero had his eyes set on equalizing Robert Lewandowski’s five goal feat from just over a week ago.
The Argentinian was the clear Man of the Match, but Kevin De Bruyne, who continues to make a mockery of Jose Mourinho’s decision to sell him to Wolfsburg 18 months ago, deserves a special mention. Kun is always calm, but I think he was very, very happy. Five goals is good and I am happy.
He must have juiced up or something, because in the second half it was all Aguero. Incredibly, they are in a worse position than a feeble Sunderland side, and that really is worrying as we head into what could be a long, dark winter.