Despite making seven changes from the side that struck late to beat Sheffield United, the Foxes ran out comfortable 2-0 winners to ensure that they are seeded in the round of 32 draw.
Cengiz Under opened the scoring for the home side, notching his first goal for his new side with a powerful volley, before Harvey Barnes' deflected shot doubled the lead and handed the East Midlands the points needed for top spot.
Formation shift benefitted Foxes
Leicester have had differing success using three central defenders but they looked a completely different outfit while using four at the back.
Defensively, Leicester looked more solid. Players were occupying their preferred positions so were better suited to their roles and the re-introduction of Wilfred Ndidi screening the back four gave the likes of James Justin and Luke Thomas license to go forward and help support the wingers on either side.
The link up play between Harvey Barnes and Thomas was especially impressive, with AEK having to eventually change formation in order to cope with the constant pressure down the left side.
The side appeared to look more balanced and were just as potent in attack as they were in defence, enjoying 16 shots while reducing the away side to three, and will surely give Brendan Rodgers a headache as he decides how to shape up in the match against Brighton and Hove Albion next.
Cengiz Under dazzles
If Under keeps performing like he has in the Europa League, Rodgers will have no choice but to start him in the Premier League.
The Turkish international was full of confidence as he was not afraid to take on defenders, run in behind and try the spectacular, something he achieved with his venomous volley that rifled into the top corner.
Another plus from his performance may be something that would excite Leicester fans, as his set piece delivery looked dangerous every time he struck the ball.
The Foxes have failed to score from a single corner this season and have been wasteful with set piece scenarios but every time Under took a corner, Leicester looked threatening.
Should Rodgers choose to start wingers in his next game, Under has certainly put his name into the mix and could be deemed unlucky not to start if he is denied a place in the first 11.
Consecutive wins boost confidence
After a difficult spell whereby the Foxes were winless in four matches in all competitions, the late winner against Sheffield United ended that run and seemingly started a winning streak as Leicester built upon that performance with a convincing win.
Leicester enjoy a lot of the ball during games but have struggled to find the finishing touch as of late but the game against AEK showed otherwise.
Two early goals put Rodgers' side in complete control and while they did not add to that lead, they looked menacing throughout. Whenever they lost the ball, they worked quickly to win it back and thanks to this, possession would be won high up the field and another attack could begin swiftly.
This was something that was not as apparent while they were out of form but as Vardy's crucial goal filled them with the confidence needed, they were able to play the way that have made them successful at the start of this season.