The LaLiga giants, as well as a number of top European Premier League sides are interested in signing the 18-year-old.
Villa boss Steven Gerrard says Chukwuemeka has been left out of Villa's pre-season tour of Australia with the player stalling on a new contract offer.
The Villans could be forced to sell the academy product, who's in the final year of his contract at Villa Park.
Chukwuemeka can sign for an overseas club for a minimal compensation fee from January.
He's made just 16 appearances for Villa's first-team, however, there are very high hopes for him.
Born in Austria to Nigerian parents, Chukwuemeka represents England at youth level.
The midfielder played a key role in England's route to glory at the Under-19 European Championship in June and July, scoring in wins against Austria as well as the Young Lions' second goal in the 3-1 win over Israel in the final.
Chukwuemeka has previously been linked with the likes of Liverpool, Manchester United and Arsenal.
Villa have been very busy this summer, making six signings so far including Philippe Coutinho on a permanent deal and defender Diego Carlos.