"I'm totally convinced that this season will be even better for him, and that playing in the Champions League against the best teams and players will take some pressure off him, because in the Europa League, he was obviously one of the two or three biggest stars".
The 18-year-old right back made his senior debut for Liverpool in October and has only started two Premier League games.
No fewer than 68 goals were scored in the second-half stoppage time in 2016-17 Premier League campaign which happens to be 6.3 percent of all goals scored last season around 0.18 goals per game.
"I opened the door for him at some stage as I had many strikers and it's important for him to play but I don't want him to go", he said.
But the Belgium global failed to convince Mourinho during their time together at Chelsea and will be playing in the Champions League proper for the first time.
The Brazil worldwide thrived under the United boss and was named Chelsea's Player of the Year during Mourinho's final season at Stamford Bridge.
The former Arsenal and Barcelona striker believes City can improve on their third-placed finish from last season because their manager simply "won't accept" anything less that a championship.
The table below shows the returns you would have obtained by investing £20 in every Premier League team throughout the 16/17 season.
Heading into his second year at Manchester United, though, there is hope, perhaps expectation, of a tilt at the Premier League title.
"We're not expected to beat teams like City".
However, United finished in sixth place and an eye-watering 24 points behind champions Chelsea, despite losing the same number of Premier League games as Mourinho's former club. "But the top seven, we are going to be in the four competitions and so there is no advantage for any one of us".
"I'm sure they will do fantastic this season".
So what can we do to get ourselves mentally prepared?
"I just think he was very clear showing that what he did a year ago was not enough for him".
Head coach Antonio Conte on Friday said there was "no news" on Costa and responded "I don't know" when asked when the striker might return to London.