The Argentina international only moved to France last summer from River Plate, but has already decided to move on to pastures new.
Originally it looked as if Liverpool were going to land the centre-back and in early July it was reported they had made an offer close to £14m.
However, it turns out that Zenit have won the race for Mammana and he has now joined them on a five-year deal.
The Russian club have parted with £14.3m to sign the 21-year-old, while Lyon will also receive 20 per cent of any future sale.