The Brazilian initially made the switch from Botafogo in the close-season, a deal which reportedly cost Marseille €5 million.
Doria was brought to the club by chairman Vincent Labrune, much to the dismay of Argentine coach Bielsa.
Bielsa has now admitted he was interested in Lucas Ocampos from Monaco, only for his superiors to ignore him.
In retaliation, Bielsa slammed the Marseille board in the press and refused to play Doria.
Now Sao Paulo have come to the youngster's rescue and haven taken him back to Brazil on loan until August.
When asked about Doria's return to his homeland, Bielsa said "Ideally, you asked these questions at the club."
"I do not know the type of operation developed."
Marseille currently sit second in Ligue 1, after occupying first place up until the turn of the year.
They face a tricky away tie at Rennes on Saturday, knowing a win could see them top the table, provided Lyon slip up at home to Paris Saint-Germain.
