Five second-half goals made it a night to remember as we booked our place in the last four of the Capital One Cup, despite trailing at half-time.
Championship Leeds, who we had not faced in nine years, took the lead through a first-half Luciano Becchio strike, but Chelsea hit back within a minute of the restart when Juan Mata curled home, and we went in front shortly after the hour thanks to a Branislav Ivanovic header.
A minute later and Victor Moses looked to have made the game safe with a low drive, and further goals from substitute Eden Hazard and Fernando Torres put the gloss on a memorable night for Chelsea supporters.
Rafael Benitez was without the suspended Ramires and Gary Cahill, while John Terry and Daniel Sturridge were still not ready for match action.
Marko Marin was included for his first Chelsea start on the right wing, with Hazard rested, while Cesar Azpilicueta and Oscar replaced the banned pair, with Ivanovic switching to centre-back. Ryan Bertrand was in for Ashley Cole at left-back.
Leeds included ex-Premier League regulars El-Hadji Diouf, Michael Tonge, Michael Brown and Jerome Thomas in their line-up, with manager Neil Warnock opting for a 4-4-2 shape.
Leeds, as expected, began the game with a high tempo, and were full of hustle and bustle, but it was Chelsea who forced the game’s first chance, when Brown misplaced a sideways pass and Mata stole in, slipping Victor Moses in. The Nigerian shot first time towards the near post, and Jamie Ashdown padded behind.
Brown, the former Tottenham and Fulham midfielder, has lost none of his fighting spirit, which borders on the rash, but Chelsea were giving as good as we got, and Lampard, the only player involved the last side these two teams met back in 2004, was the game’s first yellow card for a hefty challenge on Diouf.
Petr Cech had to be quick off his line after an Ivanovic backpass fell short, and shortly afterwards Jason Pearce headed wide from an inviting Diouf free-kick before Moses brought another save from Ashdown.
On 25 minutes Mata danced around his man inside the area and curled towards the target, a likely goal denied by a brave block from Pearce.
Chelsea had the upper hand in possession but determination was serving Leeds well, and when the Blues did give the ball away, the home side looked threatening on the break.
It was exactly through this route that they took the lead. In characteristic fashion, David Luiz attacked, but when trying to pick his pass only dinked it to the first Leedsman, and within 15 seconds we were behind, as the ball was spread wide to Thomas, and he squared across goal, to where there was a space in defence, for Becchio to power into the bottom corner.
Chelsea responded and Moses saw a strike ruled out for offside, but at the other end Tom Lees headed narrowly over after Azpilicueta had been pressured into clearing behind for a Leeds corner.
In injury time, a Lampard free-kick dipped and bent in front of Ashdown, but the goalkeeper produced a decent one-handed save to ensure his side would go in one up at the break.
Chelsea needed to quickly get back into the game, and were level within a minute as Mata curled home from the edge of the box, aided by some poor goalkeeping from Ashdown, after Torres and Moses had combined to good effect.
It was the perfect start to the second half, but Leeds almost went back in front, only a strong defensive header from Ryan Bertrand denying a simple nod home for Becchio, but we were back on level terms and now had something to build on in the remaining time.
Torres headed on target from Azpilicueta’s cross as the Blues began to get on top, but Benitez still opted to change, withdrawing Marin, who was tidy if ineffective on his full debut, and introducing Hazard.
From distance Lampard brought another save from Ashdown, with spaces beginning to show in the middle of the pitch.
It was from out wide that we would kill the game though, with two goals in a little over 60 seconds.
First, a Lampard corner was headed home at the near post by Ivanovic to give us an advantage, and a minute later, with 25 to go, Victor Moses lashed home from the edge of the box after he cut inside from Mata’s feed.
Suddenly a game that had looked, while under our control, to be in the balance, had been won. Players that looked vulnerable to the home side’s physicality looked menacing on the counter, and you sensed more goals could follow.
Hazard stung Ashdown’s palms with a powerful drive and Oscar shot straight, either side of Bertrand hobbling off with a problem, to be replaced by Cole.
Having had to absorb some pressure, we were on the attack again, and when David Luiz split the Leeds defence with a well-measured pass for Hazard, the Belgian controlled and slotted home past Ashdown to put the tie to bed.
More fun was to follow however, as Torres grabbed his goal for the evening after Lampard’s fierce shot was parried out to Hazard, who showed composure by squaring to the unmarked Spaniard to tap home.
We now head into the semi-finals, with the draw imminent, and have set about bouncing back from World Club Cup disappointment. Next up, an improving Aston Villa at Stamford Bridge on SUnday
Chelsea (4-2-3-1): Cech; Azpilicueta, Ivanovic, David Luiz, Bertrand (Cole 73); Oscar, Lampard (c); Marin (Hazard 59), Mata (Ferreira 85), Moses; Torres.
Unused substitutes: Turnbull, Ake, Saville, Piazon.
Goals Mata 46, Ivanovic 64, Moses 65, Hazard 80, Torres 82
Booked Lampard 14, Bertrand 69
Leeds United (4-4-2): Ashdown; Byram, Lees, Pearce, Peltier (c); Green, Brown (Norris 71), Tonge, Thomas (White 67); Diouf (McCormack 72), Becchio.
Unused substitutes: Kenny, Gray, Somma, Varney.
Goals Becchio 36
Referee Andre Marriner