Danny Ward's three penalty shoot-out saves sent Leicester into the fourth round of the Carabao Cup after a goalless draw at Wolves.
The visitors' dominated the first half, but their final ball was poor and they had only two misses from Adrian Silva to show for it.
They finally came close just before the break when Rachid Ghezzal's sidefoot effort was cleared off the line, but after half-time Wolves improved markedly and should have scored when Ivan Cavaleiro was played through but missed from eight yards.
An increasingly end-to-end game somehow ended goalless and it was in the shoot-out when Leicester again took the initiative, with Ward making three strong saves before Kalechi Iheanacho slotted in the winning spot-kick to give them a 3-1 penalty win.
Leicester's dominance in the opening stages was summed up better by their possession than their shot count - they had 75 per cent of the ball in the opening quarter of an hour.
The fact they did not test John Ruddy in that time was a disappointment for the Foxes, though, as Wolves' inevitable improvement finally arrived before the half-hour mark and Cavaleiro forced Danny Ward to tip an effort over from a tight angle.
Leicester did come close twice through Silva's low shot and a header over the bar, but with half-time approaching they finally came close to the opener when Ghezzal turned Marc Albrighton's cross towards goal, and Conor Coady cleared from under his own bar.
Wolves could not have been much worse after half-time, and they were a great deal better than their meagre first 45 minutes, breaking with pace and power and almost edging in front when Leo Bonatini's through-ball found Cavaleiro, who shrugged off a challenge from Ricardo Pereira, but then fired beyond the far post when through.
A late run from Albrighton forced a smart save from Ruddy at the other end when Ghezzal's cross evaded everyone, before more questionable Leicester defending from another break allowed Morgan Gibbs-White a free shot, but it was straight at Ward.
The Leicester goalkeeper, a summer signing from Liverpool, had impressed in 90 minutes but stepped it up a gear in the penalty shoot-out which followed, but not before Demarai Gray was stretchered off in injury-time with a jarred ankle, which the Foxes will hope is less serious than it could be.
Ward kept out two poor penalties from Romain Saiss and Diego Jota, before saving his best for a full-length dive to keep out Adama Traore's powerful drive.
Leicester were grateful to him after Christian Fuchs struck the bar and Hamza Choudhury's penalty was saved, but they went through when Iheanacho showed supreme confidence to wait for Ruddy to move before firing into the other corner.
Man of the match - Marc Albrighton
Danny Ward's heroics in the shoot-out were just edged by Albrighton overall for the man of the match, because of his Leicester team mate's quality of crossing and willingness with and without the ball all night.
While Ward's 90 minutes were fairly routine, Albrighton was on top form to put in three quality crosses, one of which was cleared off the line after Ghezzal's touch, and he himself came close after half-time too with an effort which was well saved by Ruddy.
What's next?
Both teams return to the bread and butter of the Premier League at 3pm on Saturday. Wolves host Southampton, and Leicester travel to Newcastle.