Argentine's team-mate has stated that the striker has his sights set on a controversial move to the Santiago Bernabeu, and claims players have known his intention for some time
The Argentinian announced on Monday his decision to leave the club, and has asked that Atletico respect his wishes to further his career.
Ujfalusi has stated that this is due to Aguero's desire to move across the Spanish capital.
The defender told Radio Sportiva. "For three or four months we [have] known he wanted to go. What is clear is [that] he has chosen to [go to] Real Madrid."
The 22-year-old has been at Atleti since joining from Independiente in 2006 and is the club's top scorer this season with 26 goals in all competitions.
'Kun' has been linked with moves to some of Europe's top clubs, including Chelsea, Inter and Juventus, but Real appear to be leading the chase. Ujfalusi added that he is unsure as to what the fan response will be to such a transfer.
He continued: "We do not know how fans will react, because there is a great rivalry. It will be a difficult decision for him."