Portugal face games against Russia and Luxembourg on November 14 and November 17 respectively.
Joao has been in sensational form since joining Wednesday from Nacional in the summer. He scored against FA Cup holders Arsenal as the Owls beat them 3-0 in the fourth round of the League Cup at Hillsborough.
He can now look forward to lining up alongside the likes of Ballon d’Or winner Cristiano Ronaldo.
Joao was born in Angola, but has represented Portugal at both Under-20 and Under-21 level.