Manchester United's mounting injury problems mean they are "in trouble" going into the season's decisive weeks, according to manager Jose Mourinho.
Mourinho lost Marcos Rojo and Zlatan Ibrahimiovic to injury during Thursday's Europa League quarter-final win over Anderlecht, the pair joining Phil Jones, Chris Smalling and Juan Mata on the sidelines.
Mourinho hopes Wayne Rooney will quickly rediscover match sharpness following his return from an ankle injury and believes Mata could play again despite previously suggesting his season was over.
"We are in trouble," Mourinho told reporters at Old Trafford.
"In this moment, Eric Bailly played six matches in a row -- 540 minutes in a row. We lost Marcos Rojo. We don't have Jones, we don't have Smalling. We are in trouble.
"Now we lose Zlatan too. But in attack, we have options. Rooney is coming. Let's see if Mata can also return before the end of the season. Let's see what happens."
Rooney has not played since United's 0-0 draw at home to West Bromwich Albion on April 1 and had become a peripheral figure even before then, but Mourinho indicated he could now play an important role.
Smalling, Jones and Rojo's injuries leave Bailly and Daley Blind as United's only fit senior centre-backs.
As a result, Mourinho also expressed reservations about 19-year-old Axel Tuanzebe's likely involvement in England's Under-20 World Cup campaign in South Korea next month.
"He has a good mentality. He's a fighter. He's a strong man," Mourinho said of Rooney, the club captain.
"Even if he's not in the best condition, if he's not in the level of sharpness that you need to play high-level football. But he has the experience, the character. So he has to (play).
"Now we need absolutely everyone. I even have to think that Axel Tuanzebe goes to the Under-Something World Cup in Korea, because maybe Axel has to come now. Now we need everybody."
- Rashford reservations -
United travel to Burnley in the Premier League on Sunday, when victory will take them to within a point of Manchester City, who welcome them to the Etihad Stadium next Thursday.
City, who play Arsenal in the FA Cup semi-finals on Sunday, occupy the fourth and final Champions League berth. United can also qualify for the competition by winning the Europa League.
Mourinho confirmed both Ander Herrera and Ashley Young will start at Burnley, having spent the 2-1 second-leg win over Anderlecht -- which secured a 3-2 aggregate victory -- on the bench.
"Herrera plays. He didn't play (against Anderlecht)," said Mourinho.
"One yellow card, he misses the semi-finals. I was thinking about (bringing on) him and (Marouane) Fellaini both at the same time, but because I did a change with Marcos Rojo, I couldn't do (it) and he couldn't play.
"So Herrera is fresh to play. Ashley Young is fresh to play. Who else? Nobody else is fresh to play."
Marcus Rashford scored United's extra-time winner against Anderlecht and looks set to deputise up front for top scorer Ibrahimovic, who is still to commit himself to United beyond the end of the season.
Rashford also scored in United's 2-0 victory over league leaders Chelsea last weekend.
Mourinho again voiced reservations about the prospect of the 19-year-old being called up by England for this year's Under-21 European Championship.
"I just feel that when a player reaches a certain level, it doesn't make a lot of sense to drop levels," said the United manager.
"It's like him going to play now in the Under-23s to win, let's say, a derby against Man City. No. (Academy coach) Nicky Butt doesn't take him to play that game. He could, by age.
"So when you reach a certain level, and he reached that level for a long time, I don't think it makes sense. But the power is in their (the Football Association's) hands."