Moritz Leitner is out for at least four weeks with a hamstring injury - but that was just the headline fitness news in a gloomy bulletin delivered by Daniel Farke ahead of Tuesday's Championship trip to Barnsley.

Injury and sickness continue to take their toll on the German's squad with Nelson Oliveira (calf) ruled out for a fortnight and Harrison Reed the latest to go down with a sickness bug which has hit Christoph Zimmermann hardest.

Alex Tettey's on-going knee problems have returned in the midst of a hectic spell of fixtures. The Norwegian is set to sit out the game at Oakwell with Farke also wary the midfielder is one booking away from a two-match suspension.

The latest doubts come with Marco Stiepermann (groin) and Tom Trybull (knee/ankle) already out until after the upcoming international break and Louis Thompson (Achilles) a longer term absentee.

Leitner's lay-off is no real surprise after he lasted only 29 minutes of Saturday's 4-3 defeat at Hull City.

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'The first diagnosis is we'll have to do without him for four weeks. Hopefully he can return pretty soon after the international break,' said Farke.

'He got a hit and he overstretched his leg and has a hamstring injury, with blood in the hamstring.

'We'll have to do without Nelson Oliveira for two weeks because he has problems with his calf. It's a strain, but there's no blood in the calf. We'll have to do without him for the next two games.

'We have to be careful with Alex because he doesn't feel 100pc comfortable with his knee.

'It's not a new injury but we have to be careful with his load – three games in a week is a big load – and also if he was booked tomorrow he would be banned for the next two games, so we have to make a decision.

'Harrison is ill. He has a temperature, and we might have to ask him to travel individually but it's doubtful he'll be available at the moment, so I will have to make a late decision.'

Farke is not planning to draft in Marcus Edwards to his depleted squad for the trip to South Yorkshire but Sean Raggett will travel with concerns over Zimmermann, who has shed six kilos in the past week through a sickness bug.

'This afternoon will be the first time Christoph will be able to train with us, so it's doubtful that he'll be available,' said Farke.

'Sean will travel with us, as it's important to strengthen our defence behaviour.

'He's always there with a great attitude, but it's a bit risky because he's never played in a three-man backline. And when you have Timm Klose and Grant Hanley as options for a two-man centre-back formation, and when Christoph is available, it can be difficult for Sean.

'But I'm pleased with his development and his attitude on the training pitch.'

• Re-live the main lines from the press conference in the blog above