The young forward has arrived from the Brazilian club, much to the anger of their fellow Premier League rivals Wolves.
Wolves felt they had an agreement with Marquinhos to secure a transfer.
However, the teenager has chosen the Gunners, and several sources states that Wolves may take legal action.
The Mirror states that Marquinhos had agreed a pre-contract with Wolves that would have started on July 14th.
Wolves believe Marquinhos has broken that agreement, and will seek legal action against the player, Arsenal, and possibly Sao Paolo as well.
Need a VPN? Or seeking to switch? Then support Tribal Football by clicking here to sign up with our official partners NordVPN. Not only will you receive the best VPN experience, but also great discounts by signing up via Tribal Football. Thanks for your support!