What Mourinho described as a "disastrous" first half performance was backed up by an improved display after the break, yet the United manager didn't try to hide his annoyance as he spoke to BT Sport after the game. "A tough time, I thought I was the luckiest manager in the Premier League".
"Defensively we were very bad".
"All I can say is Callum has been unbelievable to work with since he came to this football club", Howe said. "We are doing everything we can to get there", he said. I feel like people watching this game will not believe how hard we trained this week. "The first half, I think we learned from that and we showed that in the second half and on Wednesday you will see a difference".
Ander Herrera had been particularly influential after being introduced as a substitute for the second half. We pressed higher, more intensity and intention.
A 92nd minute victor from Marcus Rashford gave United a deserved away win.
Joao Mario capped a great individual performance with a second-half goal and also set up the other two, including for Nainggolan, who scored minutes after coming off the bench for his first appearance since injuring his ankle in the derby against AC Milan last month. "It was much better".
Former Manchester United defender David May believes the Red Devils will need Ander Herrera's presence in midfield when they take on Juventus in midweek. The lead can be overturned against teams like Newcastle and Bournemouth, but big games are coming thick and fast and United need to be ready for them from the first minute.
Jürgen Klopp predicts tight title race in ‘most exciting season for years’
On the other hand, Arsenal's backline has been a cause for concern, considering they have conceded 13 goals so far. He has never lost against the Gunners, with three wins and two draws from five matches having produced 27 goals.
"I am trying to find the balance where we develop the team in the second, third phase of attack".
"We have to defend better, we concede too many goals and risked letting in an equaliser in the 85th minute".
"I can't understand [the slow starts]".
And now Mourinho has told his team that they can only contend for the Premier League if they climb back into the Champions League positions.
He added that he was frustrated by the team continuing to start slowly, "I really can not understand the kind of [early-match] mentality that brings me more white hair!"
"But it is fantastic to have this feeling that it doesn't matter the result, we know the game is not over".
Genoa, the only team to have taken points off Juventus this season, remained 11th but only four points off fourth spot.