David Moyes will look to “galvanise” his players ahead of Saturday’s vital relegation battle at Burnley.
The 18th-placed Black Cats remained in third bottom after losing 3-1 at Manchester United yesterday.
Sunderland are two points shy of Crystal Palace in 17th place and six behind the Clarets, who they meet at Turf Moor on New Year’s Eve.
Palace, now under former Black Cats boss Sam Allardyce, are expected to pull clear of danger, but Moyes’s side can’t afford to let Burnley pull any further ahead.
“We’re going to have to try to galvanise it from within,” said the Scot.
“It’s not a situation I’m necessarily used to, but some of the players are so I hope that together we can find a way to be good enough and strong enough in the games that really matter.
“This mattered [at United], but there’ll be games when it matters more, which will be important for us.
“We are more optimistic because we’ve got a couple of results and we’re back on the tails of the other teams.
“But I said right at the start how difficult it was going to be, and that’s not going to change.
“It’ll be the same level of difficulty right to the last minute for us, I’ve got no doubt about that.”
Yesterday’s defeat was a disappointment for Moyes, who was making his first visit to Old Trafford since his sacking in April 2014.
Fabio Borini’s late strike was merely a consolation after Daley Blind’s low first-half shot and late goals by Zlatan Ibrahimovic and Henrikh Mkhitaryan.
“I knew some day I would either come up against the Manchester United players or work with some of them,” he said.
“I think that happens when you’re in football in this era.
“That’s the way it has been for me and I’ve got to say I enjoy coming back –I’ve always enjoyed coming here.
“It’s a hard place to come, a hard place to get a result and it proved to be that again.”
On the reception from United fans, he added: “I thought it was fine. I think Manchester United supporters are knowledgeable.
“They have seen some good teams, they have seen some bad teams. They are knowledgeable and I think most of them were very good.
“I am football supporter myself, so sometimes you’ll go with it, sometimes you won’t.”