Manchester United delivered a clinical first-half performance which Chelsea could not match as the Premier League champions maintained their 100 per cent start to the season with a 3-1 victory at Old Trafford.

Sir Alex Ferguson's side passed the 20-goal mark for the campaign as Chris Smalling, Nani and the in-form Wayne Rooney did the damage against one of their more likely rivals for the title.

Fernando Torres ended his goal drought in the second half, but also produced a horror miss as both teams spurned numerous chances in an end-to-end affair.

United were in front within eight minutes when Ashley Young's free-kick from the left was headed home by the unmarked Smalling, who was fractionally offside when the ball was whipped in.

Chelsea had chances to level, with Torres scuffing a weak shot wide before the Spaniard unselfishly laid a golden opportunity on a plate for Ramires, but the midfielder fired straight at David de Gea.

The title holders seized on their opponents' profligacy, and suspect defending, to increase the lead on 37 minutes when Nani, after collecting a fine cross-field pass from Jonny Evans, cut inside and, as Chelsea players stood off, unleashed a thumping drive which Petr Cech could only watch fly into the top corner.

Things got worse for Chelsea before half-time when Wayne Rooney scored the third after John Terry's attempted clearance had ricocheted into the striker's path following a stunning run from the halfway line by Phil Jones.

Andre Villas-Boas introduced Nicolas Anelka for Frank Lampard at the break and was rewarded within 30 seconds of the restart as the substitute's defence-splitting pass played in Torres to dink a cute finish above De Gea into the net.

The Red Devils should have put the match beyond Chelsea on 55 minutes, but Rooney put a penalty wide as he slipped on his run-up after Jose Bosingwa had been harshly adjudged to have brought down Nani after his fellow Portuguese's shot had crashed back off the bar.

Rooney, seeking a third successive Premier League hat-trick, then struck the post and Javier Hernandez was hurt by a crude challenge from Ashley Cole when firing the rebound into the side-netting.

Chelsea should have set up a grandstand finish when Torres went clean through again seven minutes from time but, after skipping round De Gea, he somehow put his left-footed shot wide of a gaping net.

Perhaps in an attempt to make Torres feel a tad better, United substitute Dimitar Berbatov saw a tame effort cleared off the line in injury-time by Cole, but a fourth goal would have been harsh on Chelsea, who now trail their opponents by five points.

There was nothing special about Young's eighth minute free-kick, which was floated to the far post but Terry found himself the only one defending as United shirts piled in, Smalling the man to make a connection to turn home his first league goal.

Pummelling

Chelsea did carve out a succession of opportunities that at one stage turned the game into a personal contest between the Blues and De Gea.

Having escaped unscathed from Chelsea's pummelling, United went to the other end and doubled their lead thanks to a piece of brilliance from Nani.

Questions should be asked about the ease with which Juan Mata was brushed aside but once the midfielder was out of the way, Nani advanced with confidence and drove a 20-yard effort into the top corner.

By half-time, United had a third as Terry's attempted clearance bounced off Nani and into the path of Rooney, who tapped home his ninth of the season.

The credit went to Phil Jones, although the aura surrounding the summer arrival from Blackburn was punctured by the ease with which Torres got behind him to slot home Anelka's through ball 30 seconds after the restart.

It was only Torres' second goal since arriving from Liverpool and justified Villas-Boas' decision to introduce Anelka for Lampard at half-time.

Nerves

Having already threatened on numerous occasions, Chelsea's confidence grew immediately, although United nerves would have been eased had they converted the 55th minute penalty.

Neither side will forget how Terry slipped as he went to slot home what would have been the decisive spot-kick in the shoot-out to decide the 2008 Champions League final.

On Sunday afternoon, Rooney emulated him, his standing foot giving way, the ball bouncing harmlessly wide after the striker had fired it into his own body, although the consequences were markedly different.

United might easily have had another spot-kick when Cole flew into Hernandez after Rooney had pushed a glorious chance against the post.

The tackle was not great and resulted in Hernandez hobbling down the tunnel in obvious pain as he was replaced by Berbatov but, having fired into the side netting, referee Phil Dowd felt the incident was worthy of a yellow card and no more.

Having scored once in front of the Stretford End, Torres suffered utter humiliation seven minutes from time as he raced on to Ramires' through ball, rounded De Gea and then somehow fired wide of a completely empty net.

Berbatov missed a golden opportunity himself in stoppage-time, as Cole cleared off the line after Rooney had set the Bulgarian up with an admittedly misdirected pass.

Teams 

Manchester United De Gea, Jones, Smalling (Valencia 62), Evans, Evra, Nani, Anderson (Carrick 62), Fletcher, Young, Rooney, Hernandez (Berbatov 79)
Subs Not Used  Lindegaard, Fabio, Park, Giggs
Booked  Valencia, Fletcher
Goals  Smalling 8, Nani 37, Rooney 45

Chelsea  Cech, Bosingwa, Ivanovic, Terry, Cole, Ramires, Meireles (Mikel 79), Lampard (Anelka 46), Sturridge (Lukaku 68), Torres, Mata
Subs Not Used  Turnbull, Luiz, Romeu, Malouda
Booked  Ramires, Terry, Cole
Goals  Torres 46

Attendance  75,455

Referee  P. Dowd