Conca, who joined Flamengo on a 12-month loan from Shanghai SIPG in January, has not played since suffering knee ligament damage in August.
But this week he resumed training with the ball, raising hopes of an imminent return.
“He is back doing ball work but still has some physical restrictions which make his return unpredictable,” Flamengo medical spokesman Daniel Goncalves told the Globo newspaper.
Conca is in his third stint in Rio following two separate spells with Flamengo’s cross-city rivals Fluminense.
The 33-year-old has made 46 appearances for Shanghai SIPG since joining the Chinese Super League club in 2015.
(With Inputs From Xinhua)