The 20-year-old defender made his debut for the Tottenham first team against Colchester United.
The youngster is out of contract at Spurs at the end of the season, and Mourinho has said that he will put pen to paper on a new deal.
Mourinho has also suggested that 17-year-old striker Troy Parrott will not leave on loan in the January transfer window.
Mourinho told The London Evening Standard: “I presume that Tanganga will be a player to sign a new contract.”
Mourinho added about Parrott: "He's 17 years old. I don't think at the age of 17 it's good for you to go on loan to a Championship club or to go abroad to another country. [It's] one thing if you need that step when you are 19 or 20, another thing is when you are 17.
"When you are 17 you are a baby. At 17 you just have to be in your father club where you feel at home, where you are at home, where you train and develop with the first team."
Tottenham Hotspur stay
Both Tanganga and Parrott are very talented and promising young players, and them staying at Tottenham would make sense.
Spurs do need defensive options in the coming months and years, and Tanganga could prove to be valuable in that regard.
As for Parrott, the Republic of Ireland international could become a suitable back-up to star striker Harry Kane in the coming years if he continues to progress and develop as he has done in recent times.
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