The 28-year-old, who has been linked with a move to either Real Madrid or Paris Saint-Germain, has less than a year remaining on his contract at Old Trafford and there is still some distance between both parties regarding an extension.
Although it is understood that Pogba is leaning towards signing a new deal with the Red Devils, following the arrival of Cristiano Ronaldo, his brother has confirmed that the Frenchman is unsure as to where his future lies.
"Paul has not decided yet whether to stay or not next summer. It's his decision. He's feeling very good at Man United this season. Then let's see. Let's see when it will be time to decide," Mathias told Spanish news outlet El Chiringuito TV.
This is the first time since February that Mathias has spoken out about his brother, having previously suggested that United should look to sell Pogba if they wish to avoid letting him leave for free next summer.
Pogba, who rejoined United from Juventus in 2016, has made a bright start to the new campaign, providing seven assists in just four Premier League matches.