Marcelo, a 19-year-old defender, is currently with the Buccaneers on their pre-season camp in Ndola, Zambia.
He has played in all of Pirates' friendlies, including against Congolese giants TP Mazembe at Levy Mwanawasa Stadium on Thursday.
"The Brazilian defender has done well," says a source.
"He is tall and comfortable on the ball.
"That is the kind of defender that Pirates has been looking for."
Marcelo reportedly plied his trade for Vasco da Gama last season - on loan from lower division side Nova Iguaçu FC.
Meanwhile, Morrison looks to be out of the plans of head coach Milutin Sredojevic, having not made the trip to Zambia.