Mavididi, booked for over-celebrating his first goal, then curled in a deflected killer third goal five minutes into the second half.

Wales midfielder James gave Blues hope with his second goal of the night, a right-foot chip that also took a crucial deflection - but the Foxes were never threatened again as they stretched their lead to three points over second-placed Ipswich Town.

They are also now 13 points clear of third-placed Leeds United, having picked up 55 out of a possible 66 - and that is the highest amount at this stage of a Championship season in two decades.

Wales international Jordan James also scored twice for Birmingham City

Blues started at a great pace, as Jordan James, Siriki Dembele and Krystian Bielik, with a near-post header brilliantly tipped over, all tested Foxes keeper Mads Hermansen.

But the hosts then got stung in the cruellest manner when from their own corner, after a panicking Justin crashed an attempted clearance against his own upright, Leicester broke with blistering speed and Abdul Fatawu slipped in Mavididi, who clipped a cool finish over the advancing John Ruddy.

Mavididi then rather overdid the celebration, upsetting the locals by sitting on the front wall of the home Tilton Road End.

Blues players offered their own more fitting response four minutes later, when highly regarded midfielder James latched on to Ivan Sunjic's pass to guide home a beautifully angled shot inside the left upright.

But Blues were back on level terms for just seven minutes, with Fatawu again the supply line as Leicester ran from their own box to stun Blues for a second time with the sheer speed of their counter-attacks.

Dewsbury-Hall was the scorer - his seventh strike of the season, four of which have now come against Midlands opposition, having also scored twice against Coventry on the opening day of the season and also in last month's win at West Brom.

Mavididi looked to have sealed the points when, on another rapid break, he cut in from the left and unleashed a right-foot curler which went in with the help of a deflection off Emanuel Aiwu.

Inspirational teenager James then gave Blues hope when his own deflected effort got it back to 3-2, with still time to grab a point. But, despite the introduction of substitutes Scott Hogan and Lukas Jutkiewicz, Blues were never really allowed to threaten again - and it was Leicester sub Cesare Casadei who should have added a fourth on the break, but fired just wide.

Who's next?

Birmingham travel to Plymouth Argyle this Saturday, before the Boxing Day Midlands home derby with Stoke City.

Leicester host Rotherham United this Saturday, before heading for the meeting of the top two against Ipswich on Boxing Day.

It was a closer shave than expected for Leicester in the end - much the same as the Blues manager's

Birmingham City manager Wayne Rooney told BBC Sport:

"I'm very disappointed to lose. For 30 minutes, we were very good, had control and created chances but we were naive in our defending in their first two goals.

"They scored from two counter punches - and Leicester showed the reason why they're top of the league.

"They've got some very good players. And we got punished.

"I already knew Jordan James was a good finisher. And I've been very pleased with all his performances."

Leicester City manager Enzo Maresca told BBC Sport:

"I'm very happy. We do not always try to counter-attack but sometimes we use that.

"Stephy [Mavididi] was very good. It's what we expected of him. And Abdul [Fatawu] too.

"But Stephy needs to improve his behaviour, which was not correct.

"I am pleased to be 13 points clear of third place, but we are in December. We still have many games to play."

Mavididi celebrated his first goal in front of the Birmingham fans - something his manager did not like