Inter Milan owner Massimo Moratti admitted on Thursday he is interested in signing Ronaldo from Real Madrid.
According to Spanish media reports, Real Madrid have agreed in principle to a swap loan deal with Ronaldo's Brazil international team-mate Adriano going in the other direction.
Moratti gave little away when quizzed about the proposed switch, but he did admit there was a possibilty Ronaldo would return to the club which he left four years ago to join Real.
"Anything can happen, but things also depend on other clubs, not just ourselves," Moratti told Sky Italia on Thursday, the day that the transfer window closes.
"We are not pushing it, it's something that has been in the air for some time."
The 2002 World Cup winner Ronaldo, whose contract runs till June 2008 and has a net annual salary of 7.5 million euros, is set to be back in action in several weeks after having an operation on his left tibia.
Just two days ago Ronaldo said he wanted to stay with Real.
"I am extremely happy at Real Madrid. I want to stay with the club for many years," said the three-time world player of the year and leading all-time World Cup goal scorer.
Adriano has had several well-publicised fall-outs with Inter coach Roberto Mancini and could be keen on a move to Spain.