Alex McLeish has insisted Wilfred Ndidi needs time at Leicester but can eventually replace N'Golo Kante.
The former Scotland boss signed Ndidi for just £70,000 while Genk manager two years ago and the 20-year-old joined the Foxes for £15million on Thursday.
He is expected to fill the void left by Kante who joined Chelsea for £32million in the summer having helped the club win a shock Premier League title last season.
Leicester have missed the midfielder since his Stamford Bridge switch and are 14th in the table having failed to recreate last season's form.
Ndidi became the Foxes' first signing of the transfer window and McLeish, who worked with him in 2014-15, expects him to flourish given time.
"Let's not say he's the new Kante but he has that potential," McLeish told Press Association Sport. "He can scuttle from one man to another and training would help him to do a similar role to Kante.
"Putting pressure on him and saying he's the new Kante immediately would be a big ask. (Claudio) Ranieri is a wise old owl, he has great experience and he will definitely know the way to handle the kid.
"I'm not saying he's the finished article. The Premier League is brutal and will be a test for him, if things are not going for him how will he handle it mentally? These are things that are yet to be learned."
Ndidi could make his Leicester debut in their FA Cup third-round tie at Everton on Saturday and ex-Aston Villa and Birmingham chief McLeish knows he must justify the fee having seen his value skyrocket.
"The Belgian league is not as strong as the Premier League but they are taking on a kid I signed for 100,000 euros for £15million so they must think a lot of him," he said.
"He was the only signing I made at Genk in the season I was there, I worked with the board closely and we agreed we wouldn't bring in anyone until we sold. But the recruitment scout alerted me to him, I watched some video, saw his speed and agility and said '£70,000, it's a no-brainer, sign him'.
"The market is bloated and let's face is, who is worth the money? Diego Costa cost £30million and now you're thinking that's cheap. Now when you see signings for £11million and £12million your man on the street says he can't be any good. That's the level of the Premier League, they are paying top dollar."