Andre Onana warns Harry Maguire 'to be ready' after Man United's new £47m keeper berated the defender for giving away the ball during disappointing friendly defeat by Borussia Dortmund

Andre Onana has warned Harry Maguire to stay focused at all times after the former Red Devils skipper nearly cost his side a goal with some sloppy defending during Manchester United's 3-2 loss to Borussia Dortmund on Monday.

47 minutes into the game, the Cameroonian shot-stopper gave his defender an earful for giving away possession and allowing Dortmund's attackers in on goal.

Onana managed to get a hand to Sebastien Haller's effort before Karim Adeyemi fired the follow-up wide.

Once the ball went out of play, the former Inter Milan keeper sprinted over to Maguire and berated him for the mistake.

Speaking after the game, Onana affirmed he has a good relationship with Maguire but insisted he must 'be ready' when he is on the ball.

'I try to demand a lot from him because I know he is a good player,' Onana told MUTV.

'He's one of the captains of the team. He's big, he's good with the ball so I will demand him a lot. He's a great guy, I have a good relationship with him.

'He has to be ready because when I'm on the ball I demand to everyone a lot - I start with myself because we are in this together.

'Mistakes come but we don't have to be afraid to make mistakes because this is a part of life and we learn from the mistakes.'

He added: 'We have to be very critical with ourselves. If we want to win prizes we have to demand a lot.

'It's a big honour to be here and I'm very happy to work with these guys - Harry is a fantastic player so we will move on.'

Maguire is expected to leave Old Trafford this summer after falling out of favour with Erik ten Hag.

The 30-year-old only started eight matches last season and has been transfer listed by the club.

United are understood to want £40million for the England international, which has proved to be a stumbling block for prospectus suitors.

West Ham recently had a £20m bid for the player rejected and aren't expected to go back in with an improved offer due to the wide gap in valuation between the two clubs.