Jose Mourinho admits that Manchester United are "in trouble" following a pair of nasty-looking knee injuries sustained by Marcos Rojo and Zlatan Ibrahimovic, but he has not given up hope Juan Mata could return before the season's end.

The Red Devils booked their place in the the semi-finals of the 2016-17 Europa League on Thursday night (20 April) after Marcus Rashford netted in extra-time to see off Anderlecht 3-2 on aggregate, although celebrations were tainted by the loss of two key players. Much-improved defender Rojo was carried out on a stretcher during the first half, while influential top scorer Ibrahimovic limped off at the end of 90 minutes.

United are yet to establish the severity of those issues, but Mourinho did say after the full-time whistle that he believes the early prognosis to be "fairly negative".

And while the absence of Rojo could prove particularly costly with Chris Smalling also sidelined with a knee problem and Phil Jones still recovering from a toe complaint, the manager seems slightly less concerned by losing Ibrahimovic given that captain Wayne Rooney is now fit again after ankle trouble.

Mata, feared lost for the remainder of the campaign after undergoing groin surgery, could yet play some part in the run-in.

"Eric Bailly has played six matches in a row – 540 minutes in a row," Mourinho told reporters. "We lost Marcos Rojo, we don't have Jones, we don't have 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."

Neither Smalling nor Jones are expected to return until mid-May, although Mourinho urged the England duo to "be brave" and try to do everything possible to accelerate their rehabilitation process. Daley Blind partnered Bailly at centre-back against Anderlecht after Rojo's withdrawal and 19-year-old academy graduate Axel Tuanzebe may also be afforded the opportunity to add to his one senior substitute appearance made in January's FA Cup fourth round defeat of Wigan Athletic at Old Trafford.

Zlatan Ibrahimovic
Zlatan Ibrahimovic managed to leave the field without the aid of a stretcher Reuters

Fifth-place United, currently four points adrift of the top four with a game in hand, travel to Burnley in the Premier League this weekend before meeting local rivals City in a potentially decisive rearranged derby clash next Thursday. Two stars of the recent win over Chelsea, Ander Herrera and Ashley Young, look set to start at Turf Moor after both being benched in Europe.

"Herrera plays [against Burnley]," Mourinho confirmed. "He didn't play on Thursday – one yellow card and he would have missed the semi-finals. I was thinking about him and [fellow substitute Marouane] Fellaini both at the same time but, because I made a change with Marcos Rojo, I couldn't do that and he didn't play. So Herrera is fresh to play. Ashley Young is fresh to play and who else? Nobody else is fresh to play."