Departure was mutual - Gibson
Middlesbrough chairman Steve Gibson has said that Aitor Karanka "sacrificed himself" as head coach at the Riverside.
The Spaniard left his role on Thursday following a sequence of ten league games without a victory leaving the club currently in a relegation zone and three points from immediate safety.
Steve Agnew has since taken over in a caretaker capacity as Boro prepare to host Manchester United on Sunday.
"I've had a lot of discussions with Aitor since the weekend," Gibson told The Times. "We agreed that a different approach is required.
"Aitor is tired, he has worked so hard for our football club over the last three and half years and the tension surrounding the end of last season would have taken its toll on anyone. Then we had a very busy summer.
"I know people are cynical when you say that a decision was mutual, but he wasn't sacked. He sacrificed himself. He's in a good frame of mind. I think he's relieved. He has been enormous for our club. He has progressed us and he will have learned an enormous amount from this experience."