The Super Eagles star missed the 2-0 win over Brighton last weekend due to a toe injury and will not feature in the Carabao Cup fixture against Sheffield United on Tuesday.
“Kelechi [Iheanacho] as well trained this morning,” Leicester manager Craig Shakespeare told the club’s website on Monday.
“But we need to try and improve his fitness levels.
“He’ll be training. We’ll have a decent training group and we have a decent, competitive game to play. We’re aware of that.
“He won’t feature (against Sheffield United). There’s no real major problems which is a bonus. Obviously, when players get discomfort in there, you want that to settle down by giving him a few days off the grass.
“We think we’ve done that and we’d like to push him now to see if he can improve his fitness. That’s the idea of the next three or four days.
“I think it would be too soon to throw him in (on Tuesday), although I think he would be capable of it. In the squad [to face Manchester United], there’s a possibility, yes.”
Commenting on his return, Iheanacho wrote on Twitter: “Happy to be back on the pitch.”
Iheanacho is also expected to be named in the Nigeria squad, to face Cameroon in back-to-back Russia 2018 World Cup qualifiers in September.