Wayne Rooney has said that it has been difficult to see Liverpool and Manchester City do so well this season, while United have endured constant struggles and setbacks.
Speaking to club magazine Inside United, Rooney said: "To see City doing well, and particularly Liverpool, is really difficult.
"It's not nice when we know we are capable of being up there challenging and we haven't been doing that this season.
"However, it means we have to step up and get back up there because the feeling we've had this season is not a nice feeling at all to have.
"We have to keep working, keep progressing and finish the season stronger.
Rooney accepted the players' share of the blame in the post-Ferguson slump: "As a group of players and a team we haven't been good enough this season and we have to put that right."
"After Sir Alex being here for 26 years, there was always going to be a change whoever came in and, in fairness, I think the players have to do better."
