The Argentina striker's future at the Etihad is in major doubt after manager Pep Guardiola dropped him to the bench in favour of Brazilian sensation Gabriel Jesus.
And the 19-year-old has added to Aguero's woes by scoring three times in his first two games including a stoppage time winner against Swansea yesterday.
Gabriel Jesus arrives in the UK after £27m Manchester City move
Tue, January 3, 2017
Express Sport brings you the best pictures as Gabriel Jesus arrives in Manchester
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Gabriel Jesus has arrived at Manchester Airport after his £27m move from Palmeiras
It's led to claims Aguero may leave City in the summer and Jenas believes every top club will be eyeing up a transfer.
"Like Arsenal's Alexis Sanchez or Barcelona's Luis Suarez, Aguero is a born winner – you are always going to get the best out of him when he is out on the pitch," Jenas told BBC Sport.
"Right now the biggest clubs in the world will be rubbing their hands, thinking they might be able to sign him. He turns 29 in June and is at the peak of his powers.
Sergio Aguero has been a sub in City's last two games
"Who would want him? Who wouldn't, if they can afford him? Real Madrid would take him in the blink of an eye if they could.
"Chelsea must be thinking that if Diego Costa leaves them in the summer then they would take Aguero. Even Manchester United must be watching the situation too.
"Carlos Tevez moved across Manchester when he left United so it is not impossible to go the other way and, if Aguero leaves City, it will be because they were willing to let him go."