David Moyes has urged Manchester United supporters to stick together in a letter sent to season ticket holders.
United are on course for their worst season in 25 years if they fail to overcome a two-goal deficit against Olympiakos in the Champions League in 12 days' time.
Ejected from the FA Cup and the League Cup in January, they are 12 points adrift of Manchester City in fourth, let alone the 18 points they trail Premier League leaders Chelsea.
Moyes has written a letter to supporters following the Olympiakos loss
Following the 2-0 defeat at Olympiakos, the nadir of Moyes's reign, the Scot admitted the "difficult season we have experienced was not something that I envisaged."
He wrote:
"While I knew that this job would be a challenge when I took it on, the difficult season we have experienced was not something that I envisaged, which I am sure is the case as well for you supporters – and my players, staff and I am desperate to compensate for that.
"Everywhere we turn people outside the club have a lot to say about Manchester United, but we have all stuck together through some tough times this season and I firmly believe that, in the long run, we will all come out at the other end, stronger for the experiences.
"Everything we need have been through will make us a better, stronger team and club in the future.
"Over the years you have seen great winning sides here and, in time, I have absolutely no doubt that we will see great winning sides here again.
"A big step towards that will be transforming Old Trafford back into the fortress it has long been renowned as, and we will do everything in our power to get the positive performances and results to do that, so that we can give you Season Ticket holders and all of our supporters something to shout about."
Moyes' eight months in charge of United have been a disaster
United travel to West Brom on Saturday hoping to avoid a second successive defeat to the Baggies, who won at Old Trafford for the first time since 1978 in September.