While Ndidi was on for the entire 90 minutes, Iheanacho came on for Shinji Okazaki in the 74th minute of the tie
Iheanacho, who made the starting line up, got Leicester's only chance in the first half hour, but his shot was charged down by Abdelhamid Sabiri
The summer signing picked up injury in pre-season but came through the under-23s’ win over West Ham United on Monday night at the King Power Stadium.
Summer signing Iheanacho, who has made two substitute Premier League appearances since his move, put Leicester 1-0 up from close range just before half-time.
The Blues secured a 2-1 win against Leicester at the King Power Stadium, with Alvaro Morata and N'Golo Kante grabbing the goals for Antonio Conte's men
The Nigerian players played significant role for the Super Eagles in the routing of Indomitable Lions of Cameroon in the Russia 2018 World Cup qualifier
The return fixture is on Monday in Yaounde
Manager Craig Shakespeare said he will err on the side of caution with Iheanacho, who is still recovering from an injury, which has hindered the start of his Foxes career
Iheanacho returned to training on Monday after missing the Foxes 2-0 win over Brighton & Hove Albion on Saturday.
The Nigerian international, a £25 million summer signing from Manchester City, sustained the injury at the beginning of this month in Leicester's final pre-season friendly against Borussia Monchengladbach.
The Craig Shakespeare side have yet to beat the Gunners in the Premier League era with their last league win coming in 1983, while it is a decade further back since the last time the Foxes won away at Arsenal
City have spent £25 million on the 20-year-old Nigerian, who could make his Premier League debut against the Gunners on Friday.
Iheanacho completed a £25 million move to Leicester last week after being deemed surplus to requirements by Manchester City boss Pep Guardiola.
The 20-year-old striker lasted only 17 minutes of his debut following his £25 million move from Manchester City after taking a knock on his ankle against Borussia Monchengladbach on Friday.
There was concern when Iheanacho left the King Power Stadium pitch just 18 minutes after coming on as a 66th-minute substitute for fellow striker Shinji Okazaki, following a collision with the German side's Laszlo Benes.
The 20-year-old striker had fallen down the pecking order at the Etihad Stadium following Pep Guardiola's arrival, with Sergio Aguero and Gabriel Jesus preferred to him
The 20-year-old scored 21 goals during his time in the first team at the Etihad Stadium, but made just six starts in the Premier League and Champions League last season
The 20-year-old Nigerian has agreed personal terms with the Foxes and will now head to Belvoir Drive to complete the move in the next 24 hours.
The 20-year-old has fallen further down the pecking order at Man City since the January arrival of Gabriel Jesus
Finalisation of the deal was reportedly being held up by contractual issues, including the possibility of a buy-back clause and a dispute over Iheanacho's image rights.