The forward joined the Red Devils on loan from Monaco at the beginning of the season but has found minutes on the field hard to come by under manager Louis van Gaal.
Aguero, though, believes the striker’s natural talents make him the best forward United have to offer, coming in ahead of Wayne Rooney and Robin van Persie, at least in the Argentine’s eyes.
He said: “They have a number of very talented strikers. The one who in his career has been the most predatory is Falcao.
“He isn’t having an easy time this season, but I really admire his commitment and his class and qualities are permanent.
“He is probably one of the most naturally gifted strikers in football at the moment.:
Looking ahead to this weekend’s Old Trafford encounter, Aguero added: “They are a team with a lot of great individual players, who can form an incredible unit when they work well together. But this season that has not always been the case.
“Some matches they don’t seem to play at the maximum, with the attacking qualities that they have in the team. But then in other games, they have really shown that those qualities, so they are a bit unpredictable. We know we will have to be at our very best to beat them – there’s no doubt about that.”
-Fellaini up for physical derby-
The Red Devils leapfrogged their ‘noisy neighbours’ following a 3-1 win over Aston Villa, while City remained in fourth after losing 2-1 to Crystal Palace.
The momentum is with third-placed United coming into the game after a five-game winning run, which leaves them one point clear of the Citizens.
And Fellaini is preparing himself for a very physical encounter as both teams are desperate for a win as they bid to outdo each other in the race for Champions League qualification.
“In England every game is like a derby, because it’s physical. In the derby you have to be more aggressive and more tough if you want to win,” the Belgium international said
“Everything has to be within the rules, but the physical side in England is why it’s such a competitive league.”