Sassuolo have signed Brazilian defender Marlon from Barcelona for a fee potentially rising to €12 million (£10.7m/$13.6m).
The 22-year-old found opportunities limited at Camp Nou and was recalled halfway through a two-season loan spell with Nice in order to be moved on.
Though he made just two La Liga appearances, Barca have included a buy-back option in the deal for the former Fluminense man.
Sassuolo have paid an initial €6m with the amount to be doubled if Marlon, who reportedly attracted interest from West Ham earlier in pre-season, plays 50 games for his new club.
The Blaugrana will receive 50 per cent of any future fee if he does not reach that mark.