In a second week of extracts from the brilliant new book, Brave New World, by Guillem Balague, Spurs manager Mauricio Pochettino reveals how he agonised all summer over his team's 5-1 defeat by Newcastle to end the 2015-16 season, their title hopes having being extinguished by a 2-2 draw at Chelsea.

In August 2016, having completed a pre-season tour where they played Atletico Madrid, Spurs return to London for a meeting.

Kyle Walker turns up late and Pochettino snaps...

Tottenham boss Mauricio Pochettino has had his say on Kyle Walker's last 12 months at the club

The pair had forged a strong relationship, with Walker becoming a key player for Pochettino

I don't like preparing for talks with too much detail. I think of a list of tactical topics and ask for some videos, but I don't always use them. Sometimes things might happen that make you change tack.

That's just exactly what took place during the first pre-season talk. We'd trained well with the whole squad and it was time to speak to everyone as a group. Miki [first-team coach Miguel D'Agostino] stood up with his computer. I usually stand next to him, but today I sat down to wait for the players to arrive.

Kyle Walker came into the room late. Not good. Something clicked in my head at that moment. I said to myself, 'I'm going to make a speech. But they also need to watch something.' I spoke for what seemed like half an hour. When our title hopes were extinguished after putting in such a colossal effort, finishing second turned into an insignificant prize.

We lost sight of the fact that it would still be marvellous for our fans, like winning a trophy because it would mean finishing above Arsenal.

The group lost its focus and started to be influenced by factors that, until that time, we had left in a room with a triple lock on the door. Until that game against Chelsea, that insufferable 2–2 stalemate, holidays didn't exist, nobody was focused on personal challenges at Euro 2016, transfers or improved contracts.

That draw meant the league slipped away and that door was flung wide open. Suddenly we were distracted and forgot just how important it was to win our last two games. Our performance against Newcastle explained everything. Football is a team sport and if it starts to revolve around individuals, or if your game becomes disjointed, a relegated team can put five past you.

The disappointment can make you feel like killing your players. And yourself. I spent the whole summer thinking I had to remind them when the moment came. Seeing Walker turn up late to the talk was the trigger I needed to tear into them.

Part of my talk went something like this: 'Football is a screen that shows you how a group co-exists.

But Walker departed Tottenham and joined Manchester City for £54million this summer

His final season at Spurs began with him angering Pochettino by arriving late for a meeting

'Have a look at this video. I got goosebumps watching how in the friendly the other day [in Australia against Atletico], Fernando Torres ran after a loose ball in stoppage time, after 93 minutes of slogging it out and travelling for 30 hours the day before, without sleeping well.

'The guy sprinted to try to score, when his side were winning 1-0. A player who has won everything. That is passion. That feeling that you're a footballer and you enjoy it, that's what you need.

'Not the attitude we had at Newcastle where we showed a face that does not define us as a team. We didn't seem to care and we were distant from what football is and the feeling that brought us together and got us to this point. You should be ashamed.'

And ciao. To hell with it.

We had to put that chapter to bed between ourselves and dig out all our feelings.

So I said all that and more. I spoke about things that had happened, about respect and life. We all ended up red-faced, but I liked it.

Over the season, Pochettino becomes more and more impressed with the form of Kieran Trippier and in April he starts two games against Burnley and Watford, picked ahead of Walker...

I knew there would be speculation over why I left Walker out of the starting XI, but we felt Trippier was the right pick. He didn't have a great start to the season, but he got into gear when his opportunity came.

His form dipped again over the Christmas period, but after that he kept upping his game, despite not being a regular starter. And sometimes, however much you put it off, you have to take the plunge and give a player a chance at another's expense. Leaving out a regular always wounds them, creating a rift between them and the coaching staff that can be very difficult to heal.

Walker lost his place as a guaranteed starter due to the emergence of Kieran Trippier (right)

Soon after, Walker told Pochettino that his heart and head were no longer with Tottenham

But Pochettino is stunned when Walker responds by asking for a move...

BRAVE NEW WORLD Brave New World: Inside Pochettino's Spurs by Guillem Balague is published on Oct 26 by Weidenfeld & Nicolson, priced £20. Copyright Guillem Balague, 2017. Offer price £16 (20% discount including free p&p) until Oct 29. Pre-order at mailshop.co.uk/books or call 0844 571 0640 Advertisement

Walker had just played back-to-back games for the national team. Our first match after his return was against Burnley. Trippier had been doing well in training for a few months and got the nod, meaning Walker was on the bench. We played Swansea on the Wednesday and Walker started. Trippier came back into the team to face Watford on the Saturday and was man of the match.

We won all three fixtures and were happy to have two regular starters competing for a place, with both players looking fresh for the final stretch of the campaign.

Walker came to my office after the Watford game. 'Gaffer, I've been at Tottenham for nine years. I've thought about it and my heart isn't here any more. Nor is my head. I've given all I have to give. I wanted to tell you before I tell my agent that I want to leave this summer.'

'Kyle, you have to stay professional. There's a month and a half to go. We're battling for the Premier League and FA Cup. We have to be focused and finish the campaign strongly.'

'OK, gaffer. But it's already decided.'

'Well, that doesn't just depend on you or me. It depends on the club, above all. You've disappointed me because you've decided to tell me that you want to leave when there is a month and bit left in the competition... You could've sucked it up, kept quiet, trained, played and helped the team when not picked... and at the end of the season you could have come and told me.'

Miguel was present. I always try to ensure there are witnesses during private conversations. I considered it to be an alarming lack of respect for his team-mates and a slap in the face for the club. None of that could be explained to the public at the time.

I had to bite my tongue. From that point, the rumours started to proliferate.

Pochettino was very unimpressed as Spurs were in the middle of a title battle with Chelsea

Walker made 183 Premier League appearances for Spurs, scoring four goals for the club

In November 2016, Tottenham chairman Daniel Levy invited Pochettino and his coaching staff, including assistant manager Jesus Perez, goalkeeping coach Toni Jimenez and first-team coach D'Agostino, to the estate of Joe Lewis, Tottenham's major shareholder, at Lago Escondido in rural Argentina for a week of hiking, adventure sports and meetings...

We went rafting around the lower River Manso, eight of us plus the guide. 'You'll fall off at some point,' they warned us, 'but don't worry, we won't leave you behind.' The first to take a tumble was Jesus, at the very first rapid, and the guide grabbed his leg and pulled him back in.

No sooner was the next rapid upon us than Jesus once more plunged in head first. We were all laughing, but then it started getting rougher. Still, everything was going more or less fine until the last rapid. Suddenly, the boat flipped and several members of the group were flung out. Jesus went flying, joined by Daniel [Levy], Nicolas [the caretaker of the estate], Toni and Miki, scattered in different directions. I'd promised the chairman that I'd fish him out if he fell in. I saw Daniel in the water, looking at me, a picture of seriousness.

I grabbed his hands and heaved him in. Then we joked about how I should've demanded a new contract, saying, 'Daniel, either you double our salary or you're not getting into the boat.'

Pochettino, pictured with chairman Daniel Levy in 2014, visited the estate of Joe Lewis in 2016

Pochettino (front centre), Jesus Perez (front right) and Miki D'Agostino (left) enjoyed the trip