Leeds United looked to have been dealt another injury blow last weekend minutes into the side's 3-0 defeat to Everton.
The ever-reliable Stuart Dallas was withdrawn eight minutes into the game at Goodison Park having been involved in an innocuous coming together with Alex Iwobi.
The Northern Irishman attempted to carry on but eventually signalled to the bench that he would be unable to continue.
In his place, youngster Leo Hjelde was drafted in, who also failed to finish the game.
The Norwegian could not see out the final few seconds of the match after picking up a knock on the far side of the pitch.
Marcelo Bielsa has been speaking to the media this morning, and has provided an injury update on Dallas, as well as the other currently injured players in his squad.
Throughout this week, it has been hoped that Junior Firpo would be available to make a comeback against Manchester United following a month's lay-off with a hamstring injury.
Firpo picked up the problem in the 3-2 win over West Ham United midway through January but has this week been pictured in full training with the rest of the Leeds United squad.
It is expected he will be named in Marcelo Bielsa's 20-man squad for the game this Sunday.
Leo Hjelde may require surgery if he has not recovered from a knee injury in the next three weeks, says Bielsa.
"Hjelde has an injury in his knee, and if the process of the next three weeks is effective he would be available in that time. But it could happen that he may not recover in those 20 days which would result in him having to have surgery."
Dallas is understood to have taken part in light training this week, working in the gym at Thorp Arch, but did not compete in Wednesday's 'Murderball' session, perhaps as a precaution following his premature Goodison exit.
"Dallas is recovering, he hasn't been discarded from Sunday's game," Bielsa said in his pre-match press conference, suggesting he remains in contention this weekend.
There was concern that Dallas' early substitution may lead to him spending an extended period on the sidelines, similar to the likes of Kalvin Phillips, Liam Cooper and Patrick Bamford.
Fortunately, that does not appear to be the case.
"Kalvin and Cooper continue their normal processes," he also told journalists.
The duo remain on track to return in early March.
Bielsa also added that Patrick Bamford was still battling with the foot issue which has kept him out for the last few weeks.
"He continues with the same problem," Bielsa said.
Leeds United kick-off against Manchester United at 2pm on Sunday afternoon in front of a sold-out Elland Road.
