According to boss Brian Laws, David Mirfin could be missing for up to eight weeks.
The United defender took a knock to his knee towards the end of last weekend’s FA Cup defeat to Gillingham and as a consequence missed the midweek win over Walsall.
On Wednesday, the defender also went for a scan as the Iron management tried to ascertain the extent of the damage.
Speaking after the 2-1 win over Coventry City on Saturday, boss Laws explained that not only was the injury worse than originally feared but also that Mirfin faces an extended period on the treatment table.
He told The Iron Player: “We have had the scan results and it is not looking good.
“It looks like it could be a minimum of six weeks, but maybe nearer eight.
“He has tweaked his ligament and unfortunately that’s the time this injury takes.
“But Niall Canavan has come in and grabbed his opportunity, so for us that was a bonus.
“On Tuesday he had one little flaw in his game towards the end but on Saturday he was superb.
“I am sure that Niall’s confidence will be growing with every game that goes by.”
At half time at the Ricoh Arena, the Iron replaced right-back Christian Ribeiro, with Callum Kennedy coming on in his place - a decision the boss explained was out of necessity rather than choice.
“He felt his groin in the first half,” he continued.
“It was getting tight so we felt that we had to change it.
“I thought that Callum (Kennedy) did very well when he came on.
“We know he is a left-back but as I told him it is the same position, just the other side of the pitch.
“I thought that some of his balls were excellent and he did a good job for the team.
“He allowed us to get into corners and cause problems.”
During Saturday’s win Josh Walker was shown a yellow card, meaning that he sits out next weekend’s game with Notts County.
Add to that David Prutton’s three-game ban and the Iron are a little lightweight in the centre of the park.
Over recent days there has been increased speculation of a move for former fans' favourite Matt Sparrow.
Despite admitting he would love to bring the 31-year-old back to Glanford Park, Laws admits he is more focused on what he has and the twelfth man in the stands who he feels is vital.
“Obviously we are looking in that area,” he added.
“But that is it for now as far as we are concerned, we have to concentrate on us and who we have.
“The two results of late have set us up really nicely to push on.
“Now we need the supporters to come out and back the eleven on the park.
“That’s what will be the key, whether financial or from a morale point of view.
“We need the fans to come and show their support for the team,
“So I am pleading to them, please come out - we need you.”
See much more from Brian Laws, Paul Reid and Steve Mildenhall on The Iron Player.