As England's World Cup campaign lurched perilously close to disaster, the fitness of one man occupied the thoughts of so many connected to the England team.

Jason Roy's torn hamstring, sustained days after a thunderous 153 against Bangladesh, appeared, from the outside at least, to acutely affect England.

Eoin Morgan's men lost against both Sri Lanka and Australia before returning to winning ways against India on Sunday - a victory built on a 160-run opening partnership between Roy and Jonny Bairstow.

Here, speaking to the Test Match Special podcast, Roy explains how he prepares to open the batting, the relationship with his opening partner and what it feels like to represent England at a World Cup.

When the captains go out for the toss, do you always want to bat first?

No, not at all. You want to do the best for the team and then once you know whether you are batting or bowling you can get your head round the job. I don't put too much emphasis on what happens at the toss.

I walk into the changing room and ask the lads what we're doing. If we're batting then cool, I stay nice and relaxed, get my gear on slowly and make sure I'm not ready too early. I then chat away to try to dust down the nerves a bit.

What was it like to open the batting in the opening game of the World Cup?

That game was probably the most testing mentally I've had in my career. I had a lot more time with my thoughts than I wanted.

We went in a little bit early so I had a bit too much time to prepare. So I just took myself away, chatted with the physios then started to get pads on when I felt it was the right time.

It was a bit different, but again you've got to adapt.

The fact you're facing the opening ball of the tournament goes through your head but you have to keep imagining positive thoughts and positive shots.

Do you have a routine when you get ready?

Usually from bottom to top. So I start with my pads, front pad first more often than not, box, thigh pad and then make sure when the umpires are on their way or when I cross that line I have all my gear on - gloves, helmet, bat - and I'm ready to work.

Jonny Bairstow has his own way. We don't change next to each other and I think he likes to take himself away a little bit more.

We then chat just before we go over the rope and go to work.

What do you chat about when you go out into the middle?

Normally when we are walking out and the crowd is going mad, emotions can sometimes get the better of you if you let them. So we say each other 'let's enjoy it, let's have fun', get ourselves in and reassure each other that it's just another game of cricket.

What's that adrenaline like when you are batting for England and the crowd are cheering you on?

At the start of my career I would play a shot and hear the crowd. When I'm out there now it's a very strange feeling - I don't hear a single murmur until I'm at the other end.

But it's an extremely nice feeling when you get in and go big and the crowd are going ballistic. It's a feeling like no other.

Do you always want to face first?

I tend to face first as I feel I have a better record facing first. I played a year with Hashim Amla and we took it in rotation and I felt like I batted better when I took the first ball.

You have to take a ball at some stage, so why not the first one?

If you see out the first few overs, do you and Jonny have a chat in the middle?

We have a chat at the end of every over.

It's more about reassuring yourself of what you're trying to achieve. Then when we get drinks brought to us we relay messages back to the changing room such as what a good score is, how the pitch is behaving, what to look out for, which way the wind is blowing etc.

But it's about trying to stay as relaxed as possible, especially in World Cup games. When I'm at the other end not facing I tend to look into the crowd. It's nice to switch off completely and see what you're bringing to the game; it gives you a really nice feeling.

Do you break your innings down very precisely - get to five, get to 10 etc?

I don't do it that strategically. If I'm feeling good I'll keep playing strong shots and play nice and aggressively.

Sometimes I'll need a few more balls to get myself in.

It's recognising that the deeper we take the game, with the firepower we have in the dressing room, we can score plenty.

It's also about reassuring myself. Sometimes when I was younger I may have tried to force it too early but now I take each ball as it comes.

What's the key to a good opening partnership? Do you have to like your partner?

You don't have to like each other, though it does help, but you do have to work well together. You also have to know your partner well, know their likes and dislikes.

Then when you're in the middle you feed off each other, give feedback and make sure you looking after each other.