According to a report by the Spanish newspaper Marca, the coach of Los Blancos is running out of patience with his Brazilian superstar.
In the derby against city rivals Atletico Madrid (1-2), Vini Jr. turned in another disappointing display and Mourinho hauled him off after just 54 minutes, replacing him with summer signing Yan Diomande.
What particularly appears to irritate the Portuguese head coach is the 26-year-old's extremely poor running and defensive work. On top of that, after two years, the understanding with team-mate Kylian Mbappe still is not working.
There are now even said to be thoughts about dropping the Brazilian from the starting line-up altogether and using either former Leipzig player Diomande or even Mbappe in his position instead.
Then there is Mbappe's role. The French world champion, who under Mourinho is also nominally deployed as a centre-forward, apparently keeps drifting out to the left wing not only out of habit. Up front, youngster Carlos Espi could ultimately get more opportunities after already showing his eye for goal with two strikes in four LaLiga appearances.
Getty ImagesHow much longer does Vinicius Junior have left on his Real Madrid contract?
Seven games into the Spanish top flight season, all of them starts, Vinicius Junior has managed only a single goal so far, although he has at least chipped in with four assists.
Only recently, the 26-year-old attacking star extended his Real contract on a long-term basis until 2032 and, for the time being, silenced the speculation over his future in Madrid.