The Romania International is expected to continue to larger things at the end of the season.
Estadio Deportivo says that Roma, Tottenham, Bayer Leverkusen and Villarreal are all enthusiastic about the 26-year-old.
Barcelona was also interested, but has been withdrawn in view of the recent form of Eric Garcia at Wing-back.
Ratiu's contract with Rayo has a buy -out clause of € 25 million.