Defender Marcos Rojo and midfielder Ander Herrera have not been passed fit and will miss Wolves' arrival at Old Trafford.
"I am optimistic, but it will be a hard season, yes", he said. "For sure hard season".
"We have to continue working hard in training and we know that in the Premier League we have to score".
Mourinho confirmed Sanchez who has not scored a goal in four games this season, would return on Saturday.
Mourinho said: "I think Paul, he came from the World Cup, he was the last one to come because he played the final".
"I am not saying that we are going to have more points than last season because last season we collected a very acceptable number of points".
Wolves are likely to need their top stars on form if they are to pick up a result away to United, but have already picked up a point at home to their neighbours Manchester City this season.
United, though, have conceded only once during the winning sequence.
Galaxy A7 Brings Samsung’s First Triple Camera Setup & Side Fingerprint
According to the previous leaks and a teaser image by Samsung, the Galaxy J6 Plus will boast a side-mounted fingerprint sensor . On the front, the Galaxy A7 (2018 ) sports 6-inch Super AMOLED Infinity display with Full HD+ (2220 x 1080 pixels) resolution.
Pressed on whether the 29-year-old needed to raise his game.
"Because Martial played 90 minutes and Sanchez played zero".
Explaining his decision not to field him on Saturday, Mourinho said he would only call on Dalot to play when "totally fresh" while he adapts to life at his new club.
"Maybe we have to continue working and that is the thing and I think we can do it". Football is a little bit like this.
"I think the team as a team is resolving the defensive problems better than before", Mourinho said.
"A team that yesterday looked very bad, today looks very good and yesterday looked very good, today looks very bad".
"I think we are improving as a team. It's more about the moment and the momentum, like you like to call it, is very important in the positive and negative way".
Wolves have already taken a point off defending champions Manchester City this season and are just one place below United in the Premier League table.