Manchester United have started this season very well, and one of the reasons why may be down to the acquisition of Nemanja Matic.
Man United did not have the personnel needed to mount a serious title challenge last year, and their insufficient resources eventually told as they finished in a lowly 6th place, a whopping 24 points behind winners Chelsea.
To bridge this gap, Jose Mourinho decided to break the bank with a number of summer signings; including Romelu Lukaku, Nemanja Matic and Victor Lindelof.
Although Lukaku has started the season off with a barrage of goals, it can be argued Matic has been the more important signing.
United serious missed a defensive minded midfield player last year, but this problem has been solved as the Serbian has provided the team with much needed protection in front of the back four.
But Matic, who also played under Mourinho at Chelsea, has revealed why he thinks the Portuguese manager is difficult to work with.
Speaking to the Daily Mail, the Serbian midfielder said: "Sometimes it isn't easy to work with him, because he always demands more.
"Even when you play the best match in your career, he considers that you can play better in the next match."
Although this desire to get the best out of his players may make him difficult to work with, it also shows why Mourinho has been such a successful manager.
And Matic also had words of praise for his boss, claiming he was the best manager he has ever worked with.
Matic continued: "Mourinho is a brand, and the best coach I've ever worked with.
"I co-operated excellently with him at Chelsea, and the fact that Mourinho is the coach at Manchester was the decisive fachctor in my choosing my new environment.
"Privately he's completely different from the way he is perceived by the general public.
"This is a man who possesses all human virtues. He's not at all cold or conceited, as he is presented in the media.
"He has created an excellent group of players with huge potential, and everything is there for us to achieve good results."
With Manchester United unbeaten in the Premier League and within sight of qualification to the knockout rounds in the Champions League, it is so far so good for Mourinho's side.
Although he can be difficult to work with at times, as Matic has revealed, there is no doubt that his methods bring great success to any club he manages.