The 21-year-old striker Azmoun produced solid performances in the 2015 AFC Asian Cup, where he scored two goals against Qatar and Iraq.
He reunited with his former coach Kurban Berdyev in Rostov to avoid relegation.
In late 2012, it was Rubin Kazan coach at the time, Berdyev, who convinced Azmoun to move to Russian Premier League.