Tanguy Ndombele "will be a success" at Tottenham according to Moussa Sissoko, who has backed his team-mate to win over Jose Mourinho.
Spurs forked out a club-record fee of £63 million ($79m) to lure Ndombele to England from Lyon in July 2019.
The 23-year-old was linked with a number of top European clubs, including Manchester City and Manchester United, before signing a six-year contract with the London club.
The Frenchman carved out a fearsome reputation as an all-action midfielder capable of dominating matches in the middle of the pitch at Lyon, and it was suggested that his qualities were ideally suited to the Premier League.
However, Ndombele's debut season at Tottenham has been underwhelming, with Mourinho publicly admitting he expects more from a prized asset after a 1-1 draw with Burnley in March .
It has also been reported that the two men have fallen out behind the scenes, leading to question marks over Ndombele's future in north London.
Mourinho has denied having any issue with the former Lyon star, while insisting he still has the "talent" to turn his career at Spurs around.
However, Barcelona have been credited with an interest in Ndombele ahead of the summer transfer window, and speculation is likely to increase in the coming weeks unless he is restored to Mourinho's starting line up.
Despite the fact that his international colleague has struggled to settle in at Tottenham, Sissoko is confident that he will stay put and justify the club's initial investment in the long-term.
"Maybe because I am like his big brother, I am a good example because nothing was easy for me at the beginning," the Spurs star told The Guardian .
"Tanguy's first season has not been easy for a lot of reasons, but I speak with him nearly every day. I play with him in the national team, so I know him very well.
"I told him just to stay calm, keep working every day and his time will come. I just worked very hard at training [when times were tough at Spurs] and things changed.
"We all believe in Tanguy's quality. He has come to another country, another culture, another style of football, another league, he doesn't speak the language - so there are a lot of things.
"I am sure he will be a success at the club."