Erik ten Hag has warned Manchester United players that they will not be guaranteed a place in every matchday squad.
The Red Devils have already made four signings this transfer window, bringing in Joshua Zirkzee, Lenny Yoro, Matthijs de Ligt and Noussair Mazraoui, while there are still reports that more business could be done.
Jadon Sancho, who has been linked with a move away from Old Trafford, was not involved in United's opening-day 1-0 win over Fulham last week due to an ear infection.
The 24-year-old is back at the club after a successful loan spell at Borussia Dortmund during the second half of last season. He created the fourth-most chances of any Dortmund player in the Bundesliga (25), and scored two goals, while also registering two assists.
However, Ten Hag says that with more options at his disposal this season, there is a chance that some high-profile names, like Sancho, may be on the sidelines.
"We will see [if Sancho is involved against Brighton]," Ten Hag said. "We have a squad, and I hope we will have a squad with double positioning.
"You need them all throughout the season because it is survival of the fittest.
"We have to manage it, the attitude of the players is very important, sometimes they will be disappointed they are not in the starting XI, but they have to deal with it, you win as a squad.
"The prizes are decided next May and until then we need all the players in the squad highly motivated. That is not an expectation, that is a demand on the squad. The team is always more important than any individual."
United are also reportedly close to agreeing a deal for Paris Saint-Germain's Manuel Ugarte to bolster their midfield options.
While Ten Hag did not confirm their approach for the Uruguayan, he did express his appreciation for the business already done by the club.
"They're showing we're going in the right direction," he added.
"We know as a club we have to catch up, but it shows our ambition, the way we want to go. We have done good business, very good players, quality players who will contribute to our squad and the quality of our squad."
United will face Brighton in their first away match of the Premier League season on Saturday.