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José Mourinho has repeatedly bemoaned Manchester United’s lack of ruthlessness in front of goal during his debut season at Old Trafford. To him, it has been the single biggest reason why his team have remained outside the Premier League’s top four. It was a different story here.

The game had been tight and combative until the end of the first half, with Leicester City having given as good as they got. Step forward Henrikh Mkhitaryan. The United attacking midfielder did not do much but what he did do was of the highest class.

Leicester City 0-3 Manchester United: Premier League – as it happened Read more

His breakaway finish put his team on the way to victory – it was a devastating fusion of pace and composure – while he laid on the third goal for Juan Mata early in the second half. When Mkhitaryan makes the difference like this it raises all sorts of questions as to why he struggled to make the team at the start of the season.

United went from 0-60mph at an impressive lick whereas Leicester stalled horribly. It was a tough watch for the home crowd after Zlatan Ibrahimovic had added to Mkhitaryan’s goal with his 20th of the season in all competitions and once Mata had made it three it became a procession.

United got out a few of their party tricks and it was a nice way for them to end a sticky run of three consecutive draws in the league. United had needed to win to capitalise on the losses of Arsenal and Liverpool from Saturday and they got the job done. As an aside, they still have to travel to Manchester City, Arsenal and Tottenham Hotspur.

Leicester’s implosion was total and these are the moments when it appears entirely possible they could become the first club since Manchester City in 1938 to be relegated the season after winning the top-flight title. It is now four straight losses for them in the league and they have not scored in the competition in 2017. Their trip to Swansea City next Sunday has taken on seismic importance.

Mkhitaryan had flickered during what was a scrappy first half, combining with Mata midway through it to tee up Marcus Rashford, who had started up front alongside Ibrahimovic. Rashford’s shot flew high. Mkhitaryan looked like the best bet to unlock the stalemate with his lovely touch and direct style, and so it proved.

He was too quick for Robert Huth, who had stepped up to try to repel a bouncing ball, and in a heartbeat Mkhitaryan had tapped past him and sprinted through on Kasper Schmeichel’s goal. The right-foot finish had too much on it for the goalkeeper.

Leicester looked a little sorry for themselves and, with their concentration down, United twisted the knife. Antonio Valencia was given too much time by Christian Fuchs to cross low from the right, and although Wes Morgan, Huth and Danny Drinkwater were close to Ibrahimovic, they were not close enough. The United striker spun and thumped the ball low past Schmeichel.

Leicester’s situation had been cast into a grimmer light by the victories for Hull City and Sunderland at the bottom of the table on Saturday. They had begun the day only one point above the relegation zone and they had shown fight at the outset, with Jamie Vardy leaving something on Eric Bailly, who was back in the United team for his first football since the Africa Cup of Nations.

Bailly had got to the ball first and, after the contact, he tangled with Vardy on the ground and then squared up to him once they had got to their feet. Briefly the temperature was raised; Morgan saw a header blocked by Paul Pogba and Ahmed Musa was halted by Bailly after he wanted too much time inside the area.

Mata, unusually, was at the centre of the niggle. He jumped into a reckless tackle on Vardy in the 27th minute and there could be a discussion about whether he deserved a red card rather than the yellow he received.

The referee, Anthony Taylor, got the decision right. Mata’s studs were showing but his tackling foot was not too far off the ground. Drinkwater and Fuchs were booked for first-half challenges on Mata.

Mourinho had switched to a 4-2-3-1 formation midway through the first half, with Mkhitaryan moving in behind Ibrahimovic and Rashford going to the left, and the teenager promptly worked Schmeichel with a low shot. At that point there was little to suggest United were primed to cut loose but this was a demonstration of the sort of efficiency that Mourinho had craved.

The third goal represented another dismal concession from Leicester’s point of view. Fuchs did not track Mata from Mkhitaryan’s killer pass and, with Morgan playing him onside in the middle, Mata shot coolly past Schmeichel.

Leicester had nothing in response and United had the chances to put a more emphatic slant on the scoreline, with Rashford testing Schmeichel and Mata blowing a one-on-one with a fluffed attempted lob. There were boos from the home support at the end. For Leicester these are worrying times.