Wilfred Ndidi is in contention to make his Leicester City debut in Saturday's FA Cup third-round match against Everton at Goodison Park.
The midfielder, who has signed for a reported £15million from Genk, trained with his new team-mates for the first time on Thursday.
Ranieri is impressed by how Ndidi has settled in and will make a final decision on whether to include him for the Everton tie based on Friday's training.
The Leicester manager believes the 20-year-old, a Nigeria international, will have a significant future in the game after confirming his work permit has been approved.
"Everything with the work permit is OK," Ranieri said. "He trained, he is available for Saturday and all is fine.
"Thursday was his first [training session]. He was OK and I want to see Friday before we decide whether he will play at Everton.
"We are very happy to have Ndidi here - he is a very impressive player with a great future. He is tall and jumps very well for the headers, moves the ball quickly and recovers the ball very well.
"We have followed him a lot and we hope he will very quickly impress the fans.
"He is another kind of player [to N'Golo Kante], totally different. A lot of big teams wanted him, but he prefers to come with us to improve."