Boro travel to Old Trafford on New Year's Eve before hosting champions Leicester City on 2 January. Twenty-two-year-old Fischer is Karanka's only injury absentee as he continues to recover from a knee injury suffered in the victory over Swansea City. Barragan however will also miss out for the first time in the Premier League this season after picking up his fifth booking of the season in the 1-0 defeat to Burnley on Boxing Day.
"I know how difficult it can be to play two games in such a short time," Karanka told a press conference on Thursday.
"But other teams in the league have the same task and it is my job to manage that situation. We have to be careful, but every single point is important so once again I will put out the best team to win each game."
With a space at right-back now available in the absence of the suspended Barragan, Karanka has a number of options in mind. "We have a lot of players who can play in that position," Karanka said.
"We can play with Fabio, Calum Chambers or with Emilio Nsue. So we have more than one who can replace Antonio."
Saturday's clash at Old Trafford will also see Karanka lock horns once again with old friend Jose Mourinho. The Middlesbrough boss served as Mourinho'a assistant manager for three years at Real Madrid before departing for Teeside in 2013 and lavished his old boss with praise ahead of their reunion in Manchester.
"It will be nice to see him. At the end of the game, we will share a glass of wine or beer or coke. This is one of the fixtures I was looking forward to most. I have a lot to thank Jose Mourinho for.
"I have to say thanks to him and to his staff so many times. I am in the Premier League because I learnt a lot with them. They gave me the last push to become a manager. We are really good friends and have a really good relationship."