MILLWALL go into this game against the Premier League champions off the back of a 2-0 win against League One strugglers Port Vale.
The Lions could progress to the FA Cup quarter-finals for the first time since 2013, when they eventually lost to Wigan in a semi-final at Wembley.
Leicester find themselves in a rut. The Foxes have not scored a league goal in 2017, and are sliding towards the relegation zone. With the Champions League second just four days after this tie, some focuses may have already switched to that game against Sevilla.
Lucas Ball spoke to Leicester fan Becky Taylor ahead of Saturday's sell out clash at The Den.
What made you support Leicester?: I have supported Leicester for as long as I can remember thanks to my dad. He used to go regularly, but when he started playing football on Saturdays I took on the reins of watching Leicester every week. Someone had to do it.
Why do you think Leicester have struggled so much since the turn of the year?: For me, there are a number of factors. The lack of confidence throughout the whole club at the moment is depressing, and no one dares to take risks on the pitch making us predictable.
We are really not coping without N'Golo Kante. He is an absolutely unbelievable player who did the work of two players in midfield, freeing up Danny Drinkwater to pull the strings like he can. Now, Drinkwater looks more like a League Two player.
Terrible recruitment is another factor. We desperately needed strengthening in defence, especially at right-back and centre-back, yet all we could muster in January was an on-loan-centre half (Molla Wagué) who hasn't made it into a match-day squad yet. To be fair to Wilfred Ndidi he looks like a good player, but isn't enough to save us.
Leicester are in a real rut at the moment, do you think manager Claudio Ranieri should be sacked?: It absolutely pains me to say it but he has to go.
I've got absolutely no idea who I would get in but I struggle to see where or when we will next score a (league) goal let alone get a point.
He will forever be a hero who helped us achieve the impossible but it's time to move aside to hopefully bring some energy back to a deflated team.
On a side note, I think it is horrendous that the team look as if they are not playing for him after last season, but it is much easier to sack a manager than a squad of players!
Who will Millwall have to watch out for? Who do you think that Leicester will have to watch out for from Neil Harris' side?: I think the only player who is currently coming out of Leicester's performances with any plaudits at the moment is Demarai Gray.
He runs at defenders for fun, but his decision-making still lacks prowess at times. He will cause problems.
We will probably have a changed squad, similar to the last round, so my other pick for potential decent performer is Ben Chilwell. I won't lie and pretend I know a lot about Millwall, when we were in the same leagues I knew more!
I think everyone knows of Steve Morison – I'll probably be putting money on him to score.
Finally, a score prediction?: I have called the last five correct scores for Leicester's games so hopefully my run continues as I am actually backing a 2-1 Leicester win.