The 43-year-old, who was axed last month by Middlesbrough after a poor run of form, has a good relation with United boss Jose Mourinho following their time together at Real Madrid.
Karanka and Mourinho still remain close friends, with the Portuguese criticising the Boro players for the way they treated Karanka in the final days of his four-year reign, and there is a strong possibility they may reunite at Old Trafford.
Mourinho has even warned Middlesbrough they would never be able to erase Karanka’s name or his achievements on Teesside.
“People cannot delete the good things we do in clubs,” Mourinho said. “Justice for Karanka is the work he did here. I was sacked by Chelsea. People, now, they don’t like me, but nobody there can delete what we did.
“Aitor, he took them to the play-off final and could have left the club but decided to stay. He could have left the club – and I know what I’m saying. He could have left for better. He stayed for the fans, for the owner and for the players. He had a good opportunity to go to a bigger club. I repeat, I know what I’m saying. In the end, he loses his job.”
According to The Mirror, Karanka has now been offered a role as part of the Red Devils’ coaching staff, though it’s not like Mourinho’s right-hand man.
The Spaniard is also rumoured to have received offers from La Liga clubs, however, and may consider a return to his homeland in the coming weeks.