Maguire, 25, shone with his performances for England at this summer's World Cup and his stock rose considerably in Russian Federation, convincing United that he could be the man to bolster Jose Mourinho's defence at Old Trafford.
Puel outlined some of the qualities he thought made Maguire of interest to United.
Harry Maguire impressed Ben Chilwell in Leicester's Premier League opener (AP). "I am happy with the performance to make this game in this condition, it's encouraging for the future." he commended his center-back. He is our best player.
Jose Mourinho's United emerged winners over a spirited Leicester in the season-opening Premier League fixture at Old Trafford.
"It's going to be hard away from home at Manchester United, but it's something that we're going to have to be fearless enough to try".
'It was his first season with Leicester and it's important, and he understands this, that he remains with the club for the owner for a new season and we will see after that'. But it is looking good this season.
Maguire played for Leicester against United on Friday night.
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The rally on Sunday, called Unite the Right II, is scheduled to take over Lafayette Square for two hours in the evening. Extra precautions, including a firearms ban, have been taken to help prevent violence during this year's gathering.
"Harry, he's happy also to remain with us".
'He has had a good mentality and spirit.
Puel said: "We have had good speaking with Harry recently and with the chairman also and we can not change our things just before a game and just before the new season, it is not possible for us".
"For us it is not possible". It is not serious'.
Leicester City host newly promoted Wolverhampton Wanders on next week Saturday in their next game at the King Power Stadium.
Meanwhile Croat Benkovic, 21, arrives from Dinamo Zagreb for £13m.
Puel said: "Filip is an exciting young player who has the potential to develop even more at Leicester City Football Club".