Aguero almost single-handedly revived City's Champions League hopes on Tuesday with a sensational hat-trick against Bayern Munich.
The prolific Argentina striker scored twice in the last five minutes as City came from behind to beat the 10-man Germans 3-2 in dramatic fashion at the Etihad Stadium.
Aguero has now scored 17 goals this season in 18 appearances, an emphatic return to form after being hampered by injuries in the second part of the last campaign.
Manager Manuel Pellegrini believes he is a potential future Ballon d'Or winner as world player of the year and midfielder Nasri has no doubt he belongs in elite company.
The Frenchman said: "I don't think I need to speak about his performance - the statistics speak for themselves
He is a great player on his day
He is unstoppable
Last night we needed him and he delivered.
"At the moment he is one of best players in the world
Apart from Cristiano Ronaldo, who is on another planet, he is up there with (Lionel) Messi and (Luis) Suarez.
"He has been unbelievable this year
He was last year as well, the only problem was his injury.
"This year he has been more fit and when he is one on one with the keeper it doesn't seem like he will miss the target
He always makes the difference and always delivers for us in difficult moments."
Thanks to a draw between CSKA Moscow and Roma in the other game in Group E, City had gone into the game knowing that they could not be eliminated whatever the outcome against the Germans.
But had Aguero not produced his late heroics, their prospects of qualifying, with just one game at Roma to play, would have been very slim.
Even now the equation is not straightforward but City know that with a win in the Italian capital in a fortnight they will have a strong chance - if CSKA fail to beat Bayern.
As things stand, Roma, City and CSKA are all locked together on five points.
Nasri said: "It was a great night - but just what we needed to do to keep our chances alive
We have to confirm it in Rome and win there if we want to qualify, and it still depends on Moscow against Munich.
"It is a great result, and right now everything is fantastic, but we need to win in Rome, otherwise this doesn't count."
City made a lively start as they attempted to put their dismal loss to CSKA earlier in the month aside and get back in contention in the group.
Pressure paid off as Medhi Benatia brought down Aguero in the area after 20 minutes and was sent off
Aguero tucked home the resulting penalty to open the scoring.
Bayern, already through to the knockout stages, were without a number of star players through injury and the likes of Bastian Schweinsteiger, Thomas Muller and Mario Gotze were on the bench.
But even with 10 men they were formidable, and they were ahead before the interval after goals from the brilliant Xabi Alonso and Robert Lewandowski.
City rallied in the second half but there seemed no way through until Aguero seized on mistakes by Alonso and Jerome Boateng in the 85th and 90th minutes respectively to turn the game around.
The manner of the comeback evoked memories of City's dramatic title-clinching Barclays Premier League win over QPR in 2012.
Nasri, 27, said: "We have the quality but it is always difficult at Man City - we always win in a difficult way! We won the league three years ago in the last minute.
"It is always like this but, at the same time, when we win it is special and it is fantastic for us.
"We had to win our last two games to go through
It was a miracle to still have a chance when we had only two points with two games left in the group.
"This was a miracle
At the start of the game we were winning 1-0 and when they had 10 men, I don't know why, but we stopped playing
You can't stop playing against a great team like Bayern, even if they have 10 men.
"In the second half we made some adjustments and we played better, the way we need to play if we want to qualify."
Source : PA
Source: PA