Sunderland have signed Boavista goalkeeper Mika on a two-year deal.
The 25-year-old could make his debut for the Black Cats against Everton on Monday.
Fifa have ratified the signing after a technical issue meant Boavista were unable to complete their requirements by the 23:00 BST deadline on 31 August.
Sunderland needed cover in goal after first choice Vito Mannone, 28, was ruled out for up to three months with an elbow injury.
Find all the latest football transfers on our dedicated page.