Coach Vahid Halilhodzic surprised by including uncapped French-born Mahrez after he helped Leicester City to promotion to the Premier League and recalled forward Rafik Djebbour, after his move to Nottingham Forest in January.
“I only found out about Mahrez in February and went to watch a few of his matches. He’s an interesting player,” Halilhodzic told a news conference at the Algerian Football Federation training centre on Monday.
Of Djebbour, who joined Forest from Greece, he added: “His form has improved tremendously in recent times and he’s an important player for the spirit of the squad.”
Striker Ishak Belfodil of Italian club Livorno is the only major surprise of those left out. Disciplinary problems have marked his brief international career, which began last August in a friendly against Guinea.
Algeria will take on Belgium, Russia and South Korea in Group H at the Brazil finals which start next month.
Goalkeepers: Azzedine Doukha (USM El Harrach), Rais Mbolhi (CSKA Sofia), Cedric Si Mohamed (CS Constantine), Mohamed Lamine Zemmamouche (USM Alger)
Defenders: Essaid Belkalem (Watford), Madjid Bougherra (Al Lekhwiya), Liassine Cadamuro (Mallorca), Faouzi Ghoulam (Naples), Rafik Halliche (Academica Coimbra), Nacereddine Khoualed (USM Alger), Aissa Mandi (Stade Reims), Carl Medjani (Valenciennes), Djamel Mesbah (Livorno), Mehdi Mostefa (Ajaccio)
Midfielders: Nabil Bentaleb (Tottenham Hotspur), Ryad Boudebouz (Bastia), Yacine Brahimi (Granada), Abdelmoumene Djabou (Club Africain), Sofiane Feghouli (Valencia), Adlene Guedioura (Crystal Palace), Foued Kadir (Stade Rennes), Amir Karaoui (Entente Setif), Mehdi Lacen (Getafe), Riyad Mahrez (Leicester City), Saphir Taider (Inter Milan), Hassan Yebda (Udinese)
Forwards: Rafik Djebbour (Nottingham Forest), Nabil Ghilas (Porto), Islam Slimani (Sporting), El Arabi Soudani (Dinamo Zagreb).
(Editing by Justin Palmer)