"Madders got a knock on his ankle and he looks a doubt for weekend, but we'll see how he is in recovery this week," Leicester's assistant manager Chris Davies said.

With Maddison not available for the tie at Luton and Jamie Vardy on the bench, the Foxes went with a 4-3-3 formation and played summer signing Ayoze Perez down the middle, with Gray and Marc Albrighton on the right and left respectively.

Perez set up the opener for the visitors, but had a goal ruled out in the 38th minute and is still to find the net for his new club in seven appearances since joining from Newcastle in a deal worth £30 million.

Davies said: "He is a multi-functional attacking player who can play down the side, as a central striker or as a 10. He gives us a good dynamic when he's the central striker because he can link to feet, receive the ball well and turn and bring others into play.

"He did a lot of work for the team and for him unfortunately he didn't get a goal, though I believe the one he did score was actually onside, but I think he played well in his role."

Right-back Justin caught the eye on his full debut for Leicester and Davies believes the 21-year-old "has a big future" after he scored against his old club.

The next target for the ex-Luton defender is to make his bow in the top flight – something his former team-mate Jack Stacey achieved at Bournemouth earlier this month.

"My goal to get on the pitch in Premier League and hopefully I can show people I can do it on the biggest stage," Justin added.

"We feel like this season we haven't performed as we can and we have let teams off the hook a bit.

"Obviously the Spurs game was a good game for us and we showed everyone the intensity we can play at and we feel like we can compete with the big boys."

Luton manager Graeme Jones saw positives for his team, but was also left with mixed emotions after watching Justin impress for Leicester.

"I know when you get beat 4-0 it doesn't sound like there are positives, but we tried one or two things which will help us long term. You have to take your hat off to Leicester City for what they have got," he said.

"We lost two (Justin and Stacey) in the summer and people need to understand you cannot replace them overnight because they are Premier League players."