Sheffield United: Medics are preparing to reveal the extent of John Egan's injury as Chris Wilder sweats on the defender's availability this weekend

The Republic of Ireland international has been undergoing treatment on a calf injury since being forced to withdraw from his country's UEFA Nations League tie against Denmark last night.

Although Egan's participation at New York Stadium is clearly in doubt, Chris Wilder's refusal to rule him out  of a game which could see United return to the top of the Championship suggests there is a slim possibility he could recover in time. 

"We'll know more shortly," Wilder, the United manager, admitted. "It's too early at the moment to say anything really. We're still assessing him and we'll see."

Although Richard Stearman and Martin Cranie are both waiting in reserve, losing Egan would be a major disappointment for Wilder as he prepares his tea, for the second of two back to back South Yorkshire derbies. The 26-year-old has been a driving force behind United's climb to fourth in the table after moving to Bramall Lane during the close season, with his new club conceding only 1.1 goals per game during the first 17 matches of the new campaign despite facing the likes of Middlesbrough and Aston Villa. The clean sheet they kept during the draw with Sheffield Wednesday earlier this month was their fifth since August.

Wilder is expected to use his pre-match media briefing on Thursday morning to provide an update on Egan's status. However, with United set to face both Brentford and Leeds after their meeting with Paul Warne's team, coaching staff are expected to err on the side of caution when they medics reveal the results of their findings.

Egan, who commanded a fee which could eventually rise to £4m when he left the Londoners in July, was diagnosed with the problem following Ireland's friendly with Northern Ireland last week. Enda Stevens, who also took part in that game, started yesterday's match in Aarhus. Martin O'Neill's squad, who had already been relegated to the third tier of the revamped tournament, held the Danes to a 0-0 draw.

Egan's combative approach - he suffered two concussions representing Brentford last season - means both Stearman and Cranie are expected to enjoy plenty of opportunities between now and May, while Jake Wright's imminent return to fitness, coupled with Kean Bryan's slow but significant progress following a hamstring issue, is set to further increase Wilder's options at the heart of defence.

"Every player," he said, "Every single one has to be ready to be called upon at any given time if possible. That's why it's all about the group."

With John Fleck, Ben Woodburn, Kieron Freeman and Dean Henderson also called-up by their countries following Wednesday's visit, United will wait until the last possible moment before naming their team for the trip to Rotherham; one of 11 clubs, including his present employers, Wilder represented as a player.

"The lads still here have been working hard," he said. "There's no days off if you want to achieve something, or give yourself the best possible chance."