Napoli have reportedly agreed a deal with Getafe to sign Mathias for a total €11m plus performance-related bonuses.
The 24-year-old left-back only recently signed a new contract to June 2025 and has been at the club since 2017.
According to Tuttomercatoweb, the two clubs have practically agreed the terms of the transfer, which will be a loan plus obligation to buy for a total €11m, plus up to another €3-4m in add-ons.
Juventus were among the other clubs linked with a potential bid for Mathias Olivera.
The Uruguay international has contributed one goal and two assists in 24 LaLiga appearances so far this season.
He has three senior caps under his belt for Uruguay, making his debut in January 2022.