Manchester United boss Jose Mourinho has called on ref Michael Oliver to keep his focus on Manchester City's "tactical fouling".

City have collected 42 yellow cards this season — more than any of their big six rivals — despite dominating possession more than any other team.

"It is a strategy they have. Many times they need what is called a tactical foul and then it is up to the referee to analyse and make a decision," said Mourinho, who was quick to state he was not putting pressure on Oliver.

"They put lots of people in attacking areas. They attack with a lot of players.

"When they lose the ball, they are many times unbalanced in numbers, they have lots of people surrounding the ball area and they have a very strong – and this is a great quality – transition in the next few seconds after they lose the ball.

"My answer always has to be, "the referee has to do his job" and I cannot speak about the referee."