Marquinhos is reportedly jetting off tomorrow so he can be in Rome to complete the paperwork, having agreed a one-year loan worth 1.5m with option to buy for a further 4.5m.
"We are agreed on almost everything, so there are only details to sort out," Corinthians technical director Roberto De Andrade told Lancenet.
"I think that it will all be made official on Monday at the latest."
Still only 18, Marquinhos was expected to be a fringe player at the Olimpico, but that doesn't appear to be the case.
"Roma Coach Zeman called him up and said he's never seen a player so good at restarting moves from defence after winning back the ball," his brother told news agency ANSA.
"He also said that he admires him and could play on September 2 against Inter in Milan."