CELTIC are calculating whether to bring back captain Scott Brown weeks ahead of schedule this weekend, just as they face losing his midfield team-mate Charlie Mulgrew for around a month.

It was thought Brown might be unavailable until the middle of October after a serious hamstring tear in a friendly against Rapid Vienna on July 6. The 29-year-old missed all six of their Champions League qualifiers and Scotland's Euro 2016 fixture in Germany, but manager Ronny Deila is optimistic he will be able to face Aberdeen at Celtic Park tomorrow.

"He looks very well; he could maybe play on Saturday," said Deila. "Everybody knows how important Scott is to this team. He looks good and needs minutes under his belt. He is training with the team well now. It's positive and his body is improving quickly, so that's good."

Just as Brown returns, Mulgrew will slip out of the side. Despite having played virtually all of the game in Dortmund until he was sent off in stoppage time, Mulgrew reported a problem with his knee and Celtic fear that an operation may be necessary.

"Charlie is struggling with his knee now. I don't know how long that is going to take to get better. It could be some weeks. He has a meniscus problem with his knee and it could need surgery, but I hope we don't need to do that," the manager said. Deila made light of the fact it was a fellow Norwegian, Svein Oddvar Moen, who gave Mulgrew two cautions and a red card during time added on. "At least Charlie got a rest … but I wish the referee had done it earlier."

Celtic's return to SPFL Premiership duty will feature Virgil van Dijk's first appearance since declaring himself unable to play against Dundee in the champions' last game. Van Dijk was upset that he did not get a move to the Barclays Premier League before the close of the transfer window and told Deila he was in no condition to play at Dens Park. Now, having been called up to the Netherlands squad and become a father for the first time after his partner had a baby, he is apparently available for Celtic duty again.

"I have no concerns about his commitment," said Deila. "I can see his body language and he is happy. Now he is focused on getting good results with Celtic and getting better. I hope the supporters accept that. I understand they were not happy he didn't play at Dundee, but that was also my decision. Virgil was not 100 per cent in his head. But now he is.

"He has said to me that he is so grateful to be at this club. Without the chance to play for Celtic, he wouldn't be where he is today. So he is also grateful for that. There was interest in him. But it was not even close to what we are thinking about. Also, we were not interested in selling him anyway. He is one of the players we are going to build a new team around.

"He was a little bit disappointed for a couple of days after the window closed. People want things and he was thinking he had the opportunity to go to the English Premier League. But that wasn't possible and he knows that he has a lot of challenges here as well. He is a very important player for Celtic and he has to take it as a positive. The way I saw him in training today, he has taken it fantastically well. He hasn't said anything to me about speaking about it again in January. Again, you can never plan in football. Tomorrow, he could be injured or he could start playing fantastically and become a regular in the national team for Holland. He has things to work on. He played very well against Maribor, the standard he played was Champions League level. That's why he was picked for Holland. So if he continues that, he will get his chances."