Mauricio Pochettino says it is too early to say whether Georges-Kevin Nkoudou will be a successful signing for Tottenham, and he admits the club’s “risks” in the transfer market will not always pay off.

Spurs bought Cameroonian winger Clinton Njie from French club Lyon for £10million in the summer of 2015 but the 23-year-old only spent one season at White Hart Lane.

Tottenham replaced him with another youngster from France, Nkoudou, on deadline day in August, with the 21-year-old arriving from Marseille for £11m and Njie going the other way on loan.

Three and a half months on, it remains unclear whether the Lilywhites have secured an upgrade – Nkoudou has only started one game, in the League Cup defeat at Liverpool, while making nine substitute appearances.

Tottenham have picked up some bargains in recent years by snapping up talented youngsters including England internationals Eric Dier and Dele Alli - but Pochettino admits that strategy is not always successful, and he is taking his time to assess Nkoudou.

“It’s difficult, he’s very young,” said the Spurs manager. “He’s potentially a good player but we cannot put the responsibility [on him] from day one and say ‘come on, you need to perform well. You need to work hard and understand our philosophy in a completely different culture and discipline’. It’s tough to come to Tottenham today because we’re very demanding.

“For us it’s very difficult sometimes to sign players like our opponents. When you compare us with Liverpool, Chelsea, City, Manchester United and Arsenal, in that moment it’s difficult to compete with them.

“You need to try sometimes to be clever and to take risks – and you know, in football, when you take risks sometimes you win and sometimes you lose.”

Asked if Spurs have ‘won’ this time with Nkoudou, Pochettino replied: “We’ll see, we cannot assess today. We cannot be unfair with him because it’s difficult to assess him and say ‘oh, he fails’. We only need to give him more time.

“Now it’s his first period in our club. He’s settled now but he needs to build his confidence and show his real quality.

“It’s not about money, it’s how you invest the money. It’s true that now the market is crazy. You can see how the value of players has increased. You must be clever. You need to be imaginative and creative and try to fight for good players at a very good price.

“When you’re building a stadium like we’re building, you’re not only focused on improving the team. You need to be focused on improving the team but at the same time you’re spending money to create a massive stadium which will be one of the best stadiums in Europe. I think we needed that.

“With the new stadium Tottenham will be one of the best teams in the world, that’s sure. But now we need to be creative and sometimes take a risk, and when you take a risk sometimes you win and sometimes you don’t.”

Pochettino stated in the summer that he wanted to bring in a quick attacking player, and Spurs brought in Moussa Sissoko as well as Nkoudou on deadline day.

While Sissoko has so far looked very expensive as a £30million recruit – particularly when he was omitted from the 18-man squad against Chelsea last month – he has shown encouraging signs of an improvement in his recent outings.

The France international set up Spurs’ fifth and final goal against Swansea last Saturday and he then impressed as a substitute against Manchester United at Old Trafford on Sunday, beating his full-back on a few occasions down the right flank.

“His impact was good,” said Pochettino. “That is what we need from him, that when he’s not starting he can make a real impact, and he did that against Manchester United – that’s why we gave him the last 30 minutes. I was very pleased with his performance.

“Always it’s difficult for all the players when they arrive in the Premier League, like GK Nkoudou, and Sissoko didn’t have a proper pre-season so when he arrived he struggled to get fit.

“Then they have to assimilate new concepts - we play very differently to Newcastle and his national team in France. It’s a different concept, different philosophy, everything.

“It’s normal, they need time to adapt. Some players need more, some need less, but it’s difficult to adapt their games to our style.”

Tottenham will go into the January transfer window with their head of recruitment Paul Mitchell serving out a lengthy notice period.

The 35-year-old tendered his resignation back in August, but Pochettino has revealed he is not due to leave the club – who are planning to replace him - for a while yet.

“He is still working with us and I think it will not affect the situation,” said the Argentinian. “When he handed in his notice, the notice was 16 months and he will be working until the end of the season, doing the same job.

“It’s normal, it’s difficult to find a replacement. It’s difficult to give the option to move quickly. Always it’s to protect our club and our interests.

“He is doing his job because Tottenham are paying his salary, but it’s not his decision to sign players – it is Tottenham as a club. But with him or without him, or with another person, it’s always difficult to sign players in January.”

Tottenham’s immediate focus is on Wednesday night’s home game against Hull in the Premier League, and they will be missing midfielder Mousa Dembele, who limped out of Sunday’s game at Old Trafford after suffering another blow on a troublesome foot injury.

“He is the first to feel sorry about that,” said Pochettino. “He feels bad about the situation because he plays one game and then feels some problem and he is not free like he was last season to play, play, play and help the team.

“It’s the same foot as always, it’s been a while. It’s painful on the top of his foot and it needs time and rest. It’s not a new problem.”

Follow me on Twitter @BenPearceSpurs