In a clash between two teams fighting for European places Fiorentina, in sixth, stay just ahead of Roma on goal difference.
" We felt like he was the one who would win us game, coupled with the fact he has ill-discipline in the middle of the park".
Jose Mourinho's side were poor in the first half but improved dramatically after the interval, thanks in no small part to the introduction of Ander Herrera for Fred.
United improved after the break, and almost took the lead when Young rattled the frame of the goal with a free-kick.
Romelu Lukaku did not travel with Manchester United for their game at Bournemouth on Saturday, with reports stating he was unhappy about being left out of the starting lineup for the win against Everton last Sunday.
"Even when we miss chance after chance after chance like we did in the second half they kept going until the end". We pressed higher, more intensity and intention.
Roberto Gagliardini scored in either half (14, 49), with Portuguese midfielder Joao Mario getting the fourth (90+1) and setting up three others, including Matteo Politano (16) and late substitute Radja Naonggolan (90+4) who headed in as he returned from an ankle injury.
"I started [at half-time] by saying it was impossible to play worse than we did so the second half will be better for sure. It was much better".
Allegri added, "We need to keep clear heads at all times, otherwise we can concede from the opposition's first cross and then nearly concede another from Cagliari's only chance in the second half".
"I can't believe we didn't score from the Young free-kick".
"If you concede more than 30 goals then you won't be winning the title so tomorrow we have to keep a clean sheet, so let's beat Cagliari and then we can think about Manchester United". "There were a lot of experienced winners in the dressing room, and me and Wayne were close in age with similar backgrounds and we just got on and clicked", Fletcher told Sky Sports News.
This was a start, particularly as Bournemouth had begun the season so impressively. It's a great feeling and it's bringing us closer together.