Sheffield United paid the price for a first-half penalty miss as champions Chelsea coasted to a comfortable win.
Webber's penalty miss proved costly for the Blades
Henrique Hilario had little difficulty in saving Danny Webber's poorly-taken spot-kick after Didier Drogba was adjuged to have fouled Claude Davis.
Frank Lampard put Chelsea in front just before the break, with a swerving free-kick that fooled Paddy Kenny.
Early in the second-half Lampard crossed for Michael Ballack, who made it 2-0 with a powerful far-post header.
If Webber had scored the course of the game might have been different, but once he had missed, Chelsea steadily assumed control.
Jose Mourinho's side had the better of the possession and in Lampard and Ballack, players who were able to turn that dominance into goals.
The one worry for Chelsea, who play Barcelona in midweek in the Champions League, was that the in-form Drogba did not emerge for the second half due to a foot injury.
United also lost a player in the first half, Michael Tonge limping off early on, after he fell awkardly on his ankle after tackling Joe Cole.
Before Drogba's withdrawal the Ivory Coast striker had a busy time of it - unusually in his own penalty area.
Drogba did well to slide in ahead of Claude Davis after Alan Quinn's cross had got past Hilario.
Soon after Drogba again found himself marking Davis, though this time referee Martin Atkinson ruled the Chelsea striker fouled that the United defender for a penalty.
To Chelsea's relief, Hilario comfortably saved Webber's underhit spot-kick.
Either side of Webber's penalty, both teams claimed they should have been awarded spot-kicks.
Ricardo Carvalho might have been penalised for using his arm to stop Rob Hulse's jump, while after Webber's miss Chelsea appealed when Paulo Ferriera tumbled following a Davis challenge.
It was not until the latter stages of the opening half that Chelsea began to create clear chances.
A cross from Ballack almost saw Chris Armstrong put the ball into his own net as he tried to clear under pressure from Arjen Robben.
Kenny did well to quickly to push away Lampard's close-range header, though soon after the United keeper's reactions proved altogether slower.
Lampard's long-range free-kick swerved marginally and with Kenny diving too early, the ball ended up in the middle of the net.
Lampard's goal might have had an element of fortunte about it, but there was nothing lucky about Chelsea's second.
Some slick combination play between Robben and Lampard provided the space for the England international to hang up a cross that Ballack forcefully headed in.
With a two-goal cushion, Chelsea should have won more comfortably, but Lampard shot over from a good position, while Robben was denied by Kenny after the United defence was carved apart.
Sheffield United boss Neil Warnock:
"We are a little bit naive. Their players sometimes go down where we stumble on. We have to learn what to do in certain situations.
"We will be looking to add some quality in January but we need to stick in there in the meantime.
"We are easy to referee because we never try to convince him."
Chelsea boss Jose Mourinho:
"Hilario is amazing. He is cool and comfortable in goal and I think the penalty save was a three-point save.
"If Hilario doesn't save it maybe we are in trouble."
Sheff Utd: Kenny, Bromby (Kozluk 65), Davis, Jagielka, Armstrong, Alan Quinn, Leigertwood, Tonge (Montgomery 7), Gillespie (Kabba 67), Hulse, Webber.
Subs Not Used: Morgan, Nade.
Booked: Leigertwood, Montgomery.
Chelsea: Hilario, Paulo Ferreira, Terry, Ricardo Carvalho, Bridge, Essien, Ballack, Lampard, Joe Cole (Wright-Phillips 67), Drogba (Kalou 46), Robben (Makelele 83).
Subs Not Used: Cudicini, Boulahrouz.
Goals: Lampard 43, Ballack 49.
Ref: M Atkinson (W Yorkshire).