This video can not be played Michael Carrick won 12 out of his 17 games in charge of Manchester United last season.

Manchester United boss Michael Carrick is determined to keep pushing to improve his squad this summer. Carrick is about to begin his first full Premier League campaign in charge at Old Trafford. He is acutely aware of the responsibilities that come with being the public face of such a worldwide institution, which he says it is a "privilege" to lead.

However, it also means having to address thorny issues with the media, which currently include a perceived lack of signings. Carrick says he is delighted with United's business so far – they have spent £83m to sign Andrey Santos from Chelsea and Youri Tielemans from Aston Villa, with the out-of-contract Karl Darlow also joining as back-up goalkeeper.

However, with weaknesses at left-back and in central midfield, as they prepare for a return to the Champions League after a two-year absence, Carrick knows the work cannot stop now. Because in a summer where his club missed out on key targets such as Elliot Anderson and Matheus Fernandes because they refused to match rival offers and are spending less than newly promoted Ipswich and Coventry, Carrick knows more transfer business needs to be done despite a desire to avoid the costly mistakes of the past.

"We want more, we need more, we keep looking for how we can do that," he said. "Money's money, I get that. We feel like we have to be pushing for everything we're involved in, while being realistic of what the recent history's looked like over a period of time. For now, we've got to make the most of it, but we've got to push every boundary we can to be able to win again, basically. That's the challenge."

This video can not be played Carrick signs autographs for Manchester United fans after the pre-season victory against Leeds at Croke Park.

Carrick had an excellent day on Thursday as his daughter got the A-level grades she was hoping for. He cut a relaxed figure, benefiting from a rare summer when his club have avoided draining trips further afield, instead travelling to Scandinavia for matches against Wrexham, Rosenborg, Atletico Madrid and Paris St-Germain, before facing Leeds in Dublin.

"I love the position I'm in," he said. "There's the football side; the tactical, the training, putting the team together. Then there's the other side; being the face of it, leading it, trying to set the right messages, the right behaviours and right tone for what we want to look like as a football club. I never take anything that this position and this football club brings for granted."

This video can not be played Carrick says he will treat Rashford like any other player despite being former team-mates. Carrick was given a number of opportunities to say Marcus Rashford will still be a United player when the transfer window closes on 1 September, but didn't take them. "He's our player," he kept repeating.

It was also noticeable that in talking about the England forward, he was keen to stress Rashford was not the only player in his squad he had previously coached, managed or been a team-mate of given it has been highlighted as an area of strength in the player's reintroduction.

"It is not a unique situation at all and [we] treat him exactly like any other player," he said.

However, many supporters have not forgiven Rashford for his coolness towards United during loan spells with Aston Villa and Barcelona, where everyone expected him to be this season. It is accepted even by those who know him there is a world of difference between the disinterested figure he became under Ruben Amorim and the fully motivated one who is widely accepted to be the best player to come through the club's academy since Sir Alex Ferguson retired in 2013.

Ironically, Rashford's return to United colours is likely to be against Amorim's AC Milan in Wroclaw, Poland, on Saturday. Carrick feels the 28-year-old still has a lot to offer.

"Football's got different directions," he said. "You've got to manage through the states to have a career for 10 or 15 years. It's never going to be smooth sailing. But you've got to keep moving forward. If you keep looking back too much, it doesn't do anyone any favours."

"It's been good to have Marcus around this week. He's our player. He's a good player, and he gives us something a little bit different."

Kobbie Mainoo was revitalised at United under Carrick during the second half of last season. Rashford was not the only England player to return to the United fold on Sunday evening. Kobbie Mainoo also came back.

In a sense, it feels like back to square one for Carrick with the young midfielder. When he took over from Amorim, after Darren Fletcher's two games in interim charge in January, he had to raise the confidence of a player of undoubted talent who had been virtually ignored by his boss.

At least Mainoo did come on as a substitute for Amorim in the Premier League last season. He didn't even do that for Thomas Tuchel's World Cup squad, even though it seemed England were crying out for his ball retaining abilities in the latter stages of the competition.

Carrick knows how Mainoo feels. He was similarly overlooked by Fabio Capello during the 2010 World Cup in South Africa. Carrick spoke to Mainoo "through the World Cup" and says he has been "in great spirits" this week.

"I spoke to him all the way through the World Cup, not loads, but little bits," he said. "It's challenging. From the outside we all see the glitz, the glamour and all the positive sides of football. But players are human beings. We all have our ups and downs. It's important we support each other. It was a good experience for Kobbie. It's a World Cup and that is a big step. He's still such a young man and he's achieved so much, so quickly. To be at the stage he's at is an achievement."

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