The success Aitor Karanka has enjoyed in his three years as Head Coach at Boro comes as no surprise to former mentor Jose Mourinho.
Karanka worked with Mourinho during the Portuguese's time at Spanish giants Real Madrid.
And Mourinho is now looking forward to a first head-to-head with close friend Karanka when his Manchester United side welcome the Teessiders on New Year's Eve.
"He studies, he has accumulated experiences as a player, assistant and now coach," Mourinho told Futbol Tactico.
"That makes him very capable and what he has achieved so far is not surprising at all.
"Karanka is a man with great emotional stability, very calm, with a very good personality. I just hope I can do better things!"
Mourinho says that his one-time assistant has developed during his time at the helm with Boro.
"Karanka today is a different coach to the one I knew during my time at Real Madrid," he said.
"He had two-and-a-half years of experience first as a coach in the Championship, one of the most difficult and demanding championships in Europe.
"That has made him a much better professional, coming this year to the Premier League, which in my view is the most difficult league in the world. To have that experience is very important."
The Manchester United boss hailed Karanka's character as the reason behind his successes so far.
"With me what he showed is always a very important characteristic - to be an honest person," he said.
"He's a man of loyalty and great moral principles. When you have that characteristic, no matter the profession that you dedicate yourself to, you will always have an advantage.
"Aitor has shown me that and we will have a friendship forever. I think it is the beginning of everything."