Real Madrid defender Pepe is suspended for the match against Russia at the Luz stadium on June 7 and he will also miss the friendly against Croatia on June 10.
Martins, 23, is a technically-gifted central midfielder who has impressed at Sporting this season.
Portugal's qualifying hopes for next year's finals in Brazil are in the balance as they are third in Group F, level with Israel on 11 points and one behind leaders Russia, who have two matches in hand.
Goalkeepers: Rui Patricio (Sporting), Eduardo (Istanbul BB), Beto (Sevilla).
Defenders: Joao Pereira (Valencia), Bruno Alves (Zenit St Petersburg), Fabio Coentrao (Real Madrid), Silvio (Deportivo La Coruna), Ricardo Costa (Valencia), Luis Neto (Zenit St Petersburg), Sereno (Valladolid).
Midfielders: Raul Meireles (Fenerbahce), Miguel Veloso (Dynamo Kiev), Joao Moutinho (Monaco), Andre Martins (Sporting) Custodio (Braga), Ruben Amorim (Braga), Ruben Micael (Braga).
Forwards: Cristiano Ronaldo (Real Madrid), Nani (Manchester United), Danny (Zenit St Petersburg), Silvestre Varela (Porto), Vieirinha (Wolfsburg), Helder Postiga (Zaragoza), Hugo Almeida (Besiktas), Nelson Oliveira (Deportivo La Coruna).
- Sports & Recreation
- Real Madrid
- Zenit St Petersburg
- Deportivo La Coruna