Manchester United duo Chris Smalling and Phil Jones train ahead of Celta Vigo and Arsenal clashes

The injury crisis currently engulfing Manchester United looks set to ease somewhat ahead of important matches against Celta Vigo and Arsenal, with the key quartet of Chris Smalling, Phil Jones, Eric Bailly and Paul Pogba all taking part in an opening training session at Carrington on Wednesday morning (3 May) before the club's trip to north-west Spain.

United's attempts to navigate a hectic fixture list and balance their ambitions of reaching the final of the Europa League with a desire to secure a top-four domestic finish are currently being threatened by an injury epidemic that has affected several members of Jose Mourinho's first-team squad and is also depleting their reserve and youth sides.

Top scorer Zlatan Ibrahimovic recently underwent surgery in the United States on an serious issue suffered during last month's extra-time victory over Anderlecht, while Marcos Rojo sustained his own season-ending knee injury in the same game.

Timothy Fosu-Mensah dislocated his shoulder last week and Luke Shaw is set to visit a specialist after scans on a foot problem that forced him off after only nine minutes of the recent 1-1 draw with Swansea City revealed ligament damage.

Bailly also limped out of that latter contest in the second half after a clash with striker Fernando Llorente, although a quick return to training would appear to suggest that the Ivorian has made a quick recovery. Mourinho queried after the match if his injury was related to having played 800 minutes of football during a relentlessly busy April schedule that included no fewer than nine games across all competitions.

Alongside the suspended Marouane Fellaini, Pogba was expected to be available for United's semi-final first-leg tie at Balaidos after missing the Manchester derby with a muscle injury picked up at Burnley. However, Mourinho initially cast doubt that Smalling (knee) and Jones (toe) would be fit in time to face Celta Vigo and listed full-back Matteo Darmian, veteran midfielder Michael Carrick and academy graduate Axel Tuanzebe as potential centre-back options alongside the versatile Daley Blind.

"I don't think they will," the manager said at the weekend. "That's my personal opinion, I don't think they will but I know the players I choose will give everything. It doesn't matter if I go with Darmian [as a] central defender or Carrick or Axel, I trust the boys.

"They give everything, the spirit is amazing and the group is phenomenal. Fellaini and Pogba will be back for that game so there are a little bit more in terms of options so we will give everything we have."

Neither Smalling nor Jones have played since March – when they were both injured while on international duty with England – and it remains to be seen if they will travel to Galicia or instead remain at home to continue to build match fitness ahead of potential returns at Arsenal or in the return fixture against Celta Vigo. United still have to play Tottenham Hotspur, Southampton and Crystal Palace before the end of the season and will hope to reach the Europa League showpiece in Stockholm on 24 May.