Despite not being due to turn 18 until January, Reinier has already established himself as a key figure in the Brazilian outfit's first-team squad.
The midfielder's form has allegedly resulted in interest from Barcelona, who are said to be prepared to launch an approach in one of the next two transfer windows.
However, according to reports in Spain, PSG are also monitoring the situation as they look to steal a march on their European rivals.
Reinier is said to have a £30m release clause in his contract, which is likely to lead to clubs being willing to match that fee in the near future.
The prospect has already scored six times from 10 outings for Brazil Under-17s. body check tags ::