Luke Berry is beaten the ball by Foxes striker Ayoze Perez
Goals from Demarai Gray, James Justin, Youri Tielemans and Kelechi Iheanacho were enough for the visitors to ease through as they proved far too good on the evening. To see how the Hatters rated during the contest, see below.
Would have hoped for a busy night to impress his manager and certainly got just that. Beaten four times in total, but made some fine saves to prevent it being a greater margin of defeat.
Will have learned plenty up against the quality of opponent that Leicester had. Made some good runs tracking back and timed his tackles well. Good break forward to pick out Brown for his late opportunity too.
First start in over a month and got through the 90 minutes without any concern. Couldn't make it out of his half much and didnt spot the run of Justin as the ex-Hatter made it 2-0 on the stroke of half time.
Showed further signs of his improvement this term up against a player of Perez's quality as the Spaniard was well marshalled. Comfortable enough in possession as well when pressed by the Foxes.
Stepped out of defence with real confidence and swung over some lovely crossfield balls to the right wing when he had space to do so. Put his body on the line when necessary, although underhit pass to Jones was costly late on.
Like rest of the midfield, spent most of the evening chasing shadows as Leicester had a monopoly on possession. Kept it tight when he had the ball though and managed to win the odd tackle as well.
Deserved his chance after playing well at Cardiff in the last round and one magnificent touch out wide led to a good opening. Fitness will have been boosted by the amount of closing down required.
Energy levels couldn't be questioned as he was still pressing the Foxes back-line despite the Hatters trailing 4-0. Made the odd burst in the first half but it was all too often snuffed out.
Tried to start some Town attacks in the first period as he looked to get on the ball. Often had to turn back though, such was the wall of blue in front of him. Replaced on the hour mark.
Towns best attacking player in the first period, as he was the one who appeared capable of creating something with some clever trickery. If he can stay fit, will definitely boost Hatters' Championship XI.
Thankless task on the night due to the calibre of defender he was up against. Didnt see much of the ball as Leicester, as expected, had a stranglehold on proceedings, and when he did, the support was lacking.
Had Towns best chance and only shot on target throughout the evening after a rare Luton foray forward, denied by a fine save from visiting keeper Ward's outstretched leg.
Added some space for the final half an hour as Town finally started to suggest they could grab a consolation. Unlucky to his goalbound header turned in by an offside LuaLua.
On for the closing stages in a bid to get Luton up the pitch. Handled effectively by the City defence and may well have been able to leave Cornick's header to cross the line rather than putting it in when offside.