The Catalans have confirmed that the Brazil international is set to spend a spell on the sidelines after suffering a hamstring tear
The Brazil international was replaced by Dani Alves in the 23rd minute of the tie, after injuring himself by diving to connect with a pass from teammate Andres Iniesta.
Barcelona subsequently confirmed that the player will spend a spell on the sidelines via its official Twitter account.
"Adriano suffered a hamstring tear in his right thigh. [The] approximate time out [will be] between four and six weeks," the Catalan side wrote on the website.
Barca went on to win the home clash against Rayo 3-1 thanks to an opening goal from David Villa and two goals either side of halftime from prolific goalscorer Lionel Messi.
The 28-year-old now looks set to miss both legs of his side's Champions League tie with Paris Saint-Germain, as well as the Liga meetings with Celta Vigo, Mallorca and Zaragoza.