Manchester United produced a blistering first-half performance as Premier League champions Leicester City were swept aside at Old Trafford.

Jose Mourinho's side -- without Wayne Rooney, who was dropped to the bench -- were 4-0 in front by the break thanks to goals from Chris Smalling, Juan Mata, Marcus Rashford and Paul Pogba, who opened his United account.

Although substitute Demarai Gray pulled one back for the visitors in spectacular style on 59 minutes, United coasted to a comfortable win.

Yet Leicester, who reached the interval in a state of disarray, had caused United several anxious moments before Smalling's breakthrough.

After Zlatan Ibrahimovic had hooked a volley well wide for the hosts, Islam Slimani almost found Riyad Mahrez with a chested pass inside the area before Daley Blind scrambled away a dangerous ball from Christian Fuchs.

Four minutes later, Danny Drinkwater and Daniel Amartey both had efforts from the edge of the area blocked before Robert Huth smashed a shot well over the top when the ball was played back in.

But after 22 minutes, Smalling powered a header in off Ron-Robert Zieler from Daley Blind's corner, and United took total control.

Zlatan Ibrahimovic chested down a lovely Pogba pass but blazed over the top, Marcus Rashford lashed wide after an Ibrahimovic touch and Pogba, finding his best form, saw a curling long-range strike pushed away by Zieler.

United, though, did not have to wait long to double their lead. They did so in spectacular style after 37 minutes when Mata found Pogba, whose chip forward was touched off by Jesse Lingard for Mata to smash a left-footed effort past the Foxes goalkeeper.

Three minutes later, Rashford prodded home Mata's low ball across the six-yard box to make it 3-0, and the rampant home side, pouring forward at every opportunity, made it four when Leicester's defence collapsed at a corner and allowed Pogba to thunder home a free header.

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Leicester manager Claudio Ranieri rang the changes at the break, bringing on Andy King and Gray for star men Jamie Vardy and Riyad Mahrez with an eye on their midweek Champions League meeting with Porto.

And after United had gone close again when Ibrahimovic headed wide under pressure from Huth, the champions pulled a goal back when Gray's outstanding strike from outside the area flew past David De Gea and into the top corner.

Moments later, Fuchs saw his strike from an angle blocked as the Foxes looked to narrow the gap still further, and Ranieri introduced the direct Jeffrey Schlupp for Marc Albrighton.

Ibrahimovic came close to restoring United's four-goal cushion when his low effort was tipped round the near post by Zieler.

Leicester defender Danny Simpson was booked for bringing down Rashford as he tried to break down the United left before Blind's attempted through ball to Ibrahimovic was just about scrambled away as the home side sought a fifth goal.

With 76 minutes gone, Gray forced a fine save from De Gea with another long-range swerving shot before Mourinho brought on Michael Carrick for Lingard as the game ticked towards its final 10 minutes.

And with eight minutes to go, Rooney entered the fray as a substitute for goal-scorer Rashford, with Ashley Young replacing Mata a few minutes later.