The Brazilian has been given the responsibility of replacing Swansea midfielder Michu at the Spanish club and has, so far, been impressive.
His six league goals already this season have seen him talked about as one of the rising stars in La Liga and are believed to have attracted the attention of Atletico Madrid as well as the Premier League duo.
The 20-year-old is under contract until 2015, but there is believed to be a clause in the deal that would allow him to leave for as little as £6.5m. However, Rayo may accept less than this due to financial difficulties.
Atletico are convinced that they can lure the South American away from the club, but Fulham and Sunderland are thought to be watching developments closely.
Both could make moves next month in a bid to aid their respective domestic campaigns.
Baptistao joined Rayo at just 16-years-of-age from Portuguesa Santista is his homeland.
After impressing in the club’s ‘B’ team, he found himself promoted to the senior squad, following Michu’s move during the summer.
Due to operating in a similar role, Baptistao has been likened to the Spaniard who has made a stunning start to life in English football.