Chelsea made sure that cliche game of two halves grew legs on as they marched on in the EFL Cup.
2-0 down and going into the last minute against Leicester, Gary Cahill pulled one back on the stroke of half time to renew hope.
In fact, Blues had already missed a couple of decent chances, before subs Diego Costa and Eden Hazard came off the bench. The former missed by a whisker to win it, but by then, that rare hen's tooth of a Cesar Azpilicueta goal had drawn Blues level.
He measured his right-foot shot from the edge of the box and it flew past Ron-Robert Zieler for 2-2.
It was a first goal for the defender since January, and from there on out, it was the team in black who called the shots.
Cesc Fabregas scored a cracker a minute into extra time, and his second was rifled into the net from the six yard box to shoot Foxes out of the competition.
In truth, Chelsea's defence was sloppy in the first half, and two mistakes brought a brace for Shinji Okazaki.
But although Blues rectified the mess, the major turning point was a second yellow card for Marcin Wasilewski when he forearmed Diego Costa in the 89th minute.
Leicester down to 10 men, and with Chelsea in full stride - there was only going to be one winner
OK, that's it for a pulsating night
But be sure to log on tomorrow for all the post-match reaction to a great win in Leicester for Chelsea!
Quick correction - Fabregas scores a double
...and not Eden Hazard for the third. It was all happening in those first few seconds of extra time.
RESULT: Leicester City 2-4 Chelsea (aet, score at 90 minutes 2-2)
Chelsea come back from 2-0 down to coast home against 10-man Leicester. But it needs second-half subs and a bit of class to get through.
Round-up coming next.
This is when Chelsea knew they were back with a bang. And what a hit! Cesar Azpilicueta gave the ball a right leathering to score
Still time for David Luiz to pick up a caution
The man with the mop gets the wrong side of Vardy and sends the England striker tumbling to the turf.
Does he look relieved or elated?
Half time of extra time - Leicester 2-2 Chelsea
The action has abated a bit.
Blues are coasting, and the subs have made a heck of a difference. It’s easy to see why Diego Costa and Eden Hazard write their name on first-team sheets week in, week out.
Who said the EFL cup was boring?
Let’s see; we’ve had six goals, four yellows, a red card, and a Chelsea comeback from 2-0 down.
Those who paid are also getting an extra half hour for their money.
But the next Leicester train back to London is 4.45am tomorrow morning! I hope everyone in blue has a car or a lift.
This might seem a while back
....but this was how close Diego Costa was to ending it in normal time. It passes the post by no more than a foot.
Goal! And Chelsea are on their way to the fourth round
Leicester 2-4 Chelsea
The loose ball falls to Fabregas on the six yard box and he hammers it into the back of the net.
No way back now
GOAL!!!! Leicester 2-3 Chelsea
Blues lead for the first time. It’s a great team goal that ends with Eden Hazard rifling home. Had it come a minute earlier, they wouldn’t have to play the next 29.
FULL-TIME Leicester 2-2 Chelsea - it's 30 minutes more
This game exploded in the second half. Two Chelsea goals, a heap of yellows, all subs used, and a red card for Leicester.
Will it go to penalties? City will have to defend for their lives
Final throw for Leicester too
Gray makes way for Amartey in the first minute of added time.
Leicester will finish the match with 10
Wasilewski leads with a forearm into the face of Diego Costa - and deservedly gets a second yellow card.
It’s all happening here, but it looks set for extra time
Chelsea sub - and the last throw of the dice
Pedro doesn’t look too happy with being called to the bench - but Eden Hazard is now on the pitch
The cards are piling up
Danny Drinkwater takes a swing at Diego’s shins.
It's a caution for Nemanja Matic
The Chelsea man goes into the book for a little dig at Gray
Time is up for Batshuayi. On comes...
Leicester subs to the power of two
Ulloa for Okazaki; Vardy for Ahmed Musa;
Diego Costa and Michy Batshuayi are oh, so close
Batshuayi brings a great save from Zieler who tips over, and then the sub is a coat of paint from slotting home at the far post.
On another night, that would have been a goal.
It's time for the sharp shooters
Diego Costa on for Ruben Loftus-Cheek, but Jamie Vardy is also warming up.
A chance to have a second look as Gary Cahill pulls one back
This goal, scored when it was, could prove crucial. It’s still Leicester 2-2 Chelsea
The first caution of the night goes to Leicester
Yessss!!! Leicester 2-2 Chelsea
Azpilicueta takes aim right-footed and thumps the back of the net from outside of the box - it’s hist first goal since January and it couldn’t have come at a better time
We're off in the second half. Come on, Blues!
Leicester 2-1 Chelsea
Cesc Fabregas tries a curler inside 10 seconds of the restart - but it’s comfortably gathered.
A second look at the Blues goal suggests...
...that maybe Luiz’s big mop and a brave attempted header were the real scorers of Chelsea’s strike just before half time.
It’s all about being in the right place at the right time.
HALF TIME: Leicester 2-1 Chelsea
What a lifeline!
Cahill’s header was the last action of the first half.
It should go on to sour a wasteful Blues who should have done better with first-half chances. Leicester aim twice on target - and score with them both. That’s not to say the home team hasn’t deserved the slender lead.
No doubt Conte will wait a bit longer before he brings on the big guns.
GOAL: It's one back for Blues!
Leicester 2-1 Chelsea
Gary Cahill loses Wes Morgan at the back post. It looks as if the ball had crossed the line anyway from Cahill’s header, but Luiz is on the line to make sure.
Every picture tells a story
If you had just arrived from Pluto - you would know which side was winning.
Oh no! Leicester 2-0 Chelsea
This is looking bad already.
Okazaki gets in behind again, stabs down into the ground and over Begovic. Again it crosses the line before it can be hacked clear.