Antonio Valencia's early thunderbolt put Manchester United en route to a 4-0 Premier League victory over Everton on Sunday, but they needed a flurry of late goals to finally subdue their unfortunate visitors.
Valencia belted home Nemanja Matic's crossfield pass after four minutes, but Everton responded well with United's record goalscorer Wayne Rooney, returning to Old Trafford for the first time since leaving earlier this year, wasting two good chances.
Ronald Koeman's side was still threatening an equaliser when former Everton striker Romelu Lukaku set up Mkhitaryan to side-foot United's second after 83 minutes.
Lukaku slammed in a third heading into stoppage time before Anthony Martial converted a late penalty.
United join Manchester City at the top of the table with 13 points from five games, with both sides level on goal difference.
Everton have now dropped into the bottom three.
Arsenal produced a vastly improved away performance to have the better of a 0-0 draw with Premier League champions Chelsea at Stamford Bridge earlier on Sunday.
After defeat at Stoke City and a thrashing at Liverpool, Arsene Wenger's side showed far more steel and hit the post through Aaron Ramsey as well as having Shkodran Mustafi's headed goal disallowed as they had the better of the chances.
Arsenal's draw snapped a five-match losing streak away to Chelsea in the league and left them in 12th place with seven points. Chelsea are third with 10 points.
"It was about mentality and a response from our last away game. We could have won it. It was an intense game," Wenger said. "The battle was total.
"We were focused and determined. We tried to play when we had the ball and we were close to winning the game. With a bit more freedom we would have won the game."
Wenger's side were savaged by former players and pundits after the 4-0 loss at Liverpool last month but showed far greater steel on Sunday and a point was the least they deserved.
They have still not scored away in the league this season but came close on several occasions against Antonio Conte's side who, after a lively start, were second best.
Danny Welbeck headed one good chance over and Alexandre Lacazette shot too close to keeper Thibaut Courtois after Hector Bellerin had raced to the byline and cut back an inviting pass.
Pedro wasted Chelsea's best chance in the first half when he was sent clear by Cesc Fabregas but finished tamely.
Ramsey went closest for Arsenal when he wriggled through into Chelsea's area and prodded a shot against the post with Lacazette unable to convert the rebound.
The chances dried up after the break prompting Arsenal to introduce Alexis Sanchez after he was left on the bench while Chelsea threw on Eden Hazard for Willian.
Mustafi thought he had won it for Arsenal when he met a free kick with a downward header but he was adjudged offside.
Arsenal's hearts were in their mouths when Hazard slalomed through and pulled the trigger but his fierce rising drive was well held by the perfectly-positioned Petr Cech.
A disappointing Chelsea display ended on a sour note when Luiz followed through recklessly on Kolasinac and referee Michael Oliver reached for his red card.
"We have great respect for officials, but it is strange to finish a third game in a row against Arsenal with 10 men," Conte said. "You need to see what happened before the tackle."