Matter of time before Pogba shows his quality: Mourinho

United's manager says it is just a matter of time before the French midfielder demonstrates his natural quality at Old Trafford following an underwhelming spell since his landmark 89 million pounds ($115.71 million) move from Juventus in August.

Pogba started well with a dynamic display in United's 2-0 Premier League home win over Southampton last month, prompting Mourinho to say "I couldn't be happier with him" after the game.

Yet the 23-year-old, who helped France to the Euro 2016 final in July, was anonymous in United's defeat by Manchester City last week and gave another underwhelming performance in the 1-0 loss at Feyenoord in the Europa League on Thursday.

"The world-record player is always a question, but I want Paul to forget that and to play his football," Mourinho said before taking United to Watford for Sunday's Premier League match.

"(Having had) no pre-season, he had a very good impact in the first game and it's normal that, after that, he has a little decrease.

"But I'm full of trust in him because I know the player he is; I know he's a very good guy with a lot of ambition, so the form will come naturally. As the team improves, form improves."

Mourinho also believes the world transfer record tag is misleading.

"You make a relation between what you pay and the club revenue, and realise that other clubs paying 20, 30, 40 (million pounds) is a much bigger thing than what Man United did," Mourinho told reporters.

($1 = 0.7692 pounds)