MANCHESTER -- Jose Mourinho has said Manchester United will need Wayne Rooney's fighting spirit and that they are "in trouble" after injuries to Zlatan Ibrahimovic and Marcos Rojo.
Ibrahimovic and Rojo suffered knee problems as United won 2-1 against Anderlecht at Old Trafford to progress to the semifinals of the Europa League.
Mourinho said the outlook for both was "fairly negative," and with the injured Chris Smalling, Phil Jones and Juan Mata already out of forthcoming games against Burnley and Manchester City, the manager finds his options limited at a crucial time.
But with United and England captain Rooney fit again following a recent ankle injury, Mourinho said he would rely on the 31-year-old to support Marcus Rashford and Anthony Martial.
"He has a good mentality, he is a fighter," he said. "He is a strong man. Even if he is not in the best condition, even if he is not in the level of sharpness that you need to play high-level football, we need him.
"He has the experience and character, so he has to [be ready]. Now we need absolutely everyone.
"We are in trouble. In this moment, Eric Bailly has played six matches in a row, and we have lost Rojo, we don't have Jones or Smalling, we are in trouble and now we lose Zlatan too.
"But in attack, we have options. Rooney is coming, and let's see if Mata can also return before the end of the season. Let's see what happens."
Mourinho will make changes to the team that finished Thursday's game against Anderlecht by recalling Spanish midfielder Ander Herrera's for Sunday's trip to Burnley.
"Herrera plays," he said. "He didn't play against Anderlecht because one yellow card and he would miss the semifinal.
"I was thinking about bringing on him and Marouane Fellaini both at the same time, but because I did a change with Rojo I couldn't.
"He didn't play, so Herrera is fresh to play, Ashley Young is fresh to play, and who else? There is nobody else to play."