The 51-year-old has praised the Nigeria international for the recent impressive form of the King Power Stadium outfit
The 24-year-old midfielder suffered a groin injury at the start of the season which kept him out of action for about three months.
Ndidi returned from injury against Sheffield United on December 12 and helped the Foxes secure victory in the encounter.
Leicester City have won four of their last five games since the Nigeria international came back from the groin problem, including a 2-0 win over Tottenham last time out.
The Foxes’ impressive performances ensured their progress on the Premier League table to second spot after gathering 27 points from 14 games.
Sherwood has credited Leicester’s run of fine form to the solid defensive displays from the Super Eagles star and believes with the midfielder, Brendan Rodgers’ men can extend their winning form when they take on Manchester United on Boxing Day.
“They have got Ndidi back, I think he’s given them an injection of energy which they have been missing in that midfield area, to supplement Tielemans and Dennis Praet,” Sherwood told Premier League Production.
“Maddison’s come back to life because they’ve got their energy in the midfield area and if Manchester United fullbacks leave, Vardy would be sprinting in there, he would be hurting them and stretching them down the sides.”
Ndidi has been a consistent performer for Leicester City since he teamed up with the club from Belgian side Genk in 2017.
Last season, the Nigeria international played 32 league games for the King Power Stadium outfit to help them finish fifth on the Premier League table and secure a Europa League ticket.
In the current campaign, Ndidi has only made eight appearances across all competitions for the Foxes, including six in the English top-flight due to his injury problems.
The midfielder will be expected to be on parade when the King Power Stadium outfit takes on Manchester United.
Ndidi is also a key member of the Nigeria national team and has played more than 30 games for the West African side.
His recent injury problem forced him to miss the Super Eagles’ last Africa Cup of Nations qualifiers against Sierra Leone but will hope to return to the side in their next outing in the campaign.