Jose Mourinho believes Manchester United have been found wanting for motivation in a difficult start to the season, but is expecting a big response from his side in Saturday's visit to West Ham. United begin the weekend sitting seventh, eight points off the top of the Premier League, after defeats to Brighton and Tottenham and being held to a 1-1 draw at home by Wolves last Saturday after three straight wins.
That was followed on Tuesday by elimination from the League Cup on penalties at home by Championship side Derby County after a 2-2 draw at Old Trafford.
"I sometimes feel frustrated because with the work we do, I'm always expecting more," said Mourinho on Friday.
"It looks that when we feel we are really improving and playing better and having a good run of results there is always a little going down in terms of the focus or the motivation. I feel that."
Mourinho has also had the distraction of a clash with midfielder Paul Pogba having stripped the Frenchman of his role as vice-captain on Tuesday, and seen video footage of a standoff between the pair at training on Wednesday go viral.
The Portuguese insisted that Pogba will return to his starting line-up at the London Stadium having impressed with his attitude in training this week.
And unlike in recent times when Mourinho has been criticised for his negative outlook, he backed his side to beat a West Ham side on the up having won at Everton and held Chelsea in their last two league outings.
"I expect to win tomorrow. I expect to play very well tomorrow. We worked very, very well - especially on Wednesday and Thursday, so tomorrow I expect a very good performance and I expect to win a very difficult match," said Mourinho
"I don't come here and say the training session was not very good, that the players are not committed and that I have a bad feeling."
Mourinho's problems with Pogba are just the latest in a series of fall outs he has had with members of the United squad in just over two seasons in charge.
Luke Shaw and Anthony Martial have previously been in the firing line, but he refuted suggestions his players are struggling to deal with the demands of representing the 20-time English champions.
"I don't think any player is afraid to play for the club," added Mourinho.
"If I put myself in the position of a journalist, maybe people think that sometimes the boys are not committed, maybe people can think the manager doesn't demand enough from them, maybe people think on the training ground we don't train enough this area or that area. That's quite frustrating.
"But I repeat that tomorrow I think we are going to play very well, I think we are going to win a very difficult match against a very good opponent, an opponent with great investment, an opponent with a champion manager (Manuel Pellegrini) with lots of experienced players and lots of very talented players."