First half goals from Layvin Kurzawa and Radamel Falcao were added to in the second 45 when Marcel Tisserand raced clear of the defence to produce a subtle finish that sealed the result.
Nigel Pearson’s Foxes had plenty of positives to take from the performance however, and had chances to get on the score sheet themselves though Matty James, Chris Wood and Neil Danns, but it wasn’t to be.
City once again started with the same 3-5-2 formation that worked so well in the 1-0 pre-season win at Port Vale, with a back three of Zak Whitbread, Wes Morgan and Sean St. Ledger being flanked by Paul Konchesky and Ritchie De Laet.
Wood and Jamie Vardy started up front, while as expected, AS Monaco named a strong starting XI that included Radamel Falcao, Joao Moutinho, Jeremy Toulalan and Richardo Carvalho.
The Foxes began extremely brightly though, with Danny Drinkwater getting to the byline and setting up Matty James for a shot that was tipped impressively around the post by Danijel Subasic.
Claudio Ranieri’s Monaco side responded with a couple of efforts from range – the latter from Moutinho resulting in a corner from the left on seven minutes.
The Portuguese international took it and found the head of left back Kurzawa at the near post, who glanced the ball past Kasper Schmeichel from all of three yards to make it 1-0.
It was an entertaining start to the half, and despite the visitor’s lead, City were still able to create opportunities – the best coming when Wood picked up a Danny Drinkwater ball on the right and unleashed a vicious 12 yard effort that Subasic pushed wide.
For Monaco though, the significant skills of Falcao were beginning to shine through as his smart run was picked out by Mounir Obbadi’s diagonal ball, but a magnificent save from Schmeichel six yards out thwarted the Colombian.
But with five minutes left in the half, Falcao finally got on the score sheet, and there was little Schmeichel could do about it – Andrea Raggi’s run down the right produced an excellent low cross that landed at the Colombian’s feet for a tap-in.
Pearson made wholesale changes in the second half as the side reverted to a 4-4-2 but lost none of its creativity – Anthony Knockaert cutting inside from the right and firing a thunderous shot that was deflected just wide.
The visitors were formidable opponents though and they fired a warning shot on the hour mark when Lucas Ocampos drove a low shot across goal and just wide, moments before Monaco themselves made a host of substitutions.
On came the likes of James Rodriguez and Jakob Poulsen to replace first half stars such as Falcao and Moutinho for Ranieri’s men, who were enjoying the lion’s share of the possession.
Substitute Lloyd Dyer was proving to be City’s best outlet on the left wing as the game went through a quiet period, but Monaco’s Favio Tavares was a formidable opponent at full back.
But by far City’s best opening came with 15 minutes left to play, and Schlupp was the architect.
The striker found bags of space on the left and pulled a ball back for Neil Danns on the edge of the box – however the midfielder’s shot struck Knockaert on its way to goal, much to the relief of the Monaco ‘keeper.
City boss Pearson then handed a debut to summer signing Zoumana Bakayogo in the 77th minute, in place of Drinkwater.
Monaco continued to test Schmeichel from range in the closing stages, but the Danish international was more than up to the challenge while at the other edge City, despite some excellent play, were unable to find that breakthrough.
With four minutes left the result was left in little doubt when Tisserand raced through on goal to put the visitors 3-0 up with a deft finish into the bottom corner.
City: Schmeichel, De Laet (Waghorn 46), Konchesky (Schlupp 46), Drinkwater (Bakayogo 77), Morgan (c), Whitbread (Danns 46), James (Marshall 46), Vardy (Moore 46), King (Knockaert 46), St. Ledger (Gallagher 60), Wood (Dyer 46).
Subs not used: Logan.
AS Monaco: Subasic, Kurzawa, Carvalho, Moutinho, Falcao, Ocampos, Ferreira-Carrasco, Obadi, Abidal, Raggi, Toulalan.
Subs: Tavares, Rodriguez, Poulsen, Maraval, Germain, Isimat-Mirin, Kagelmacher, Ndinga, Dingome, Roma, Wolf, Tisserand, Pi, Riviere, Caillard
Goals: Kurzawa 7, Falcao 40, Tisserand 85
Referee: Kevin Friend
Attendance: 10,633