Leeds showed the unpredictable side of the Championship promotion race as they claimed a top-three scalp for the second time in four days.
Luciano Becchio put Leeds in early control from the penalty spot as they followed up their weekend win over then-leaders Crystal Palace.
It came after an emotional Elland Road paid tribute to former idol Gary Speed before kick-off, on the anniversary of his death, and the home side did not take long to take a grip on proceedings.
Just three minutes in, Leicester full-back Jeff Schlupp needlessly tripped defender Sam Byram just inside the area.
Becchio duly converted his 12th goal this term with an unstoppable spot-kick past Kasper Schmeichel.
Leicester’s defending quickly got better and Nigel Pearson’s promotion hopefuls responded with in-form winger Ben Marshall. After 13 minutes, his determined right-wing run carried him half the length of the field before Marshall produced a low, near-post shot which Paddy Kenny fielded comfortably.
Minutes later, Leeds defender Alan Tate was fortunate not to suffer Schlupp’s fate, as his trip on Martyn Waghorn came inches outside the penalty area.
Marshall, again, took the free-kick but could only hit a well-constructed wall.
El-Hadji Diouf, currently in talks with Leeds over extending his short-term contract beyond the end of January, offered a threat from set-pieces but, following the early aberration, Leicester’s defending was showing a vast improvement.Schmeichel dealt unconvincingly with one such corner, but escaped punishment. Diouf then picked out Tom Lees but the centre-half failed to make clean contact.
Becchio’s excellent ball into the near-post was met by Paul Green on the half-volley, Schmeichel responding with a superb one-handed tip over the crossbar.
But Marshall was again instrumental when Leicester came close to claiming an equaliser, his dangerous cross only being half cleared and falling for Waghorn whose volley flashed across the goal and off the bar.
Waghorn opened the second half by continuing Leicester’s momentum when he found himself ahead of the Leeds defence but ran directly into trouble.
And centre-half Wes Morgan rose well to meet a Waghorn freekick but could only guide it directly into Kenny’s waiting arms.
Anthony Knockaert, one of a double substitution made by Leicester before the hour, unleashed a fierce 25-yard shot which Kenny kept out at full stretch as the pressure mounted.
Leeds substitute Michael Brown momentarily eased the strain on the hosts when he curled a shot just wide from 20 yards.
But Marko Futacs ensured that Leeds were once more anxiously counting down the minutes when the home defence failed to deal with a Danny Drinkwater free-kick and the 6ft5in forward fired a spectacular attempt just wide.