The experienced striker left Al-Duhail by mutual consent in July after just seven months with the Qatari side.
But the word from Russia is that a deal has been agreed for the 34-year-old to join Lokomotiv.
Sport Express states that Mandzukic is expected to arrive in Moscow on Wednesday for medical tests.
Mandzukic, who has not played any football since March, will sign a two-year deal worth €2.8m-per-season plus bonuses.
The retired Croatian international has enjoyed a successful career playing for the likes of Bayern Munich, Atletico Madrid and Juventus.