The former Huddersfield Town player, impressive in recent weks in the Reds' mini-upturn, suffered the problem in last weekend's game with Middlesbrough and missed today's 2-0 loss at Derby.

Williams will need undergo surgery.

Asbaghi said: "It was after the game against Middlesbrough. Unfortunately, he injured his knee and he will be out for the rest of the season.

"It is bad timing as Jordan was playing at a really good level before he got injured. The team with Jordan was playing well and the timing is not good.

"But one when door closes, another opens and I am confident that the other players that will get the chance in his absence will definitely take it and do good for Barnsley."

A mistake from Williams' replacement Callum Brittain helped Ravel Morrison score the killer second goal just after the break in the Reds' hugely disappointing loss at relegation rivals Derby.

Morrison had put the Rams ahead midway through the first half following a polished move,

Despite the best efforts of Carlton Morris, the support cast was pitiful with Barnsley looking a pale shadow of the side who came into the game with three victories in their previous four matches to inspire hope of another 'Great Escape' act.

The Reds now have three home games, starting with a match against Stoke in midweek, with the main good news on the day coming in the fact that relegation rivals Reading lost at home to Millwall.

On a poor loss to Derby, Asbaghi added: "Of course, it is a big disappointment for us with the result and we knew the importance of this game. I think over ninety minutes, we have to play better than we did to give us the chance to collect the three points that we wanted.

"I think Derby started the game better than us and put on some pressure and then they scored a goal. I cannot analyse the goal exactly, I felt it was a little bit suspiciously offside from my part.

"But I think our reaction after was pretty decent and (Carlton) Morris had a one-v-one. We got into the game more.

"We spoke about small details to improve and felt confident of doing better. But it did not take long in the second half and we lose the ball and they score.

"Mentally, it was really tough in this arena in front of their fans and it put us in a situation which was too difficult to overcome.

"What needed to improve was move the ball even faster and our decision-making, technical (qualities) and winning second balls has been much better than we showed today. It is definitely something we need to improve as we have a game coming in a couple of days."

Barnsley FC's Poya Asbaghi confirms major injury blow for Reds