​Toby Alderweireld was part of the Tottenham team that reached the Champions League final under Mauricio Pochettino [Getty Images]Mauricio Pochettino heads to Old Trafford with a reputation for “brutal” pre-seasons, an obsession with fitness and a no-nonsense approach.Manchester United confirmed on Friday that Pochettino will become their manager on 18 November – replacing Michael Carrick – and has signed a contract until June 2029.So what should the players and staff expect when the Argentine takes control at the end of next week?BBC Sport spoke to Toby Alderweireld, who spent four years playing for Pochettino at Tottenham during a successful period where they reached the Champions League final and finished second in the Premier League.How Ferguson-inspired Pochettino can succeed where Carrick failed at Man UtdPochettino a decade in Man Utd’s making – but Carrick deserves better’The main man’Alderweireld, 37, says Pochettino has a no-nonsense approach to management and that he can get the best out of a squad, as long as you do it his way.”He is very approachable but you need to follow his plan. If you don’t follow his plan, you go on the side and you’re not coming back any more.”You need to think about team, team, team. If you’re thinking about yourself, you’re gone.”As a player you have your own life, your own situation but he says ‘look, I understand and you can talk to me about it but the team is number one’ – that’s the way it is and if you’re not following it, he’ll put you on the sideline.”He’s straightforward, has his own ideas and maybe you agree with them or don’t, that’s up to you. But you need to follow him and I think that’s something Manchester United need – a big character, everyone in the same direction, following the plan and if not, no problem, you can go. He’s the main man.”He’s a very smart man, knows how to talk to the press and what to say. He will create an environment like ‘it’s us against the world’ – we are getting fit, we are together as a team. It doesn’t matter what people say, let’s work together and get results together. “At Spurs there was coaching staff but he will be there. He knows everything. If he’s not there, he’s looking at video and data. He knows everything about the players on and off the pitch – the players will be watched.”He is, in a positive way, a control freak because he says your body is your weapon and it needs to be ready to perform.”‘The basic is to be fit’Manchester United have been criticised this season for an apparent lack of fitness and for not running enough in games – they rank in the bottom five in the league for distance covered and most high-intensity runs.Alderweireld says Pochettino’s number one demand is fitness and running.”First of all he made us very fit. Pre-season was brutal. “The way he wants to play – on the front foot, putting people under pressure, a high line, very dynamic play – you need to run. You need to be capable of running and be capable of high intensity runs – the