What do you think the US Open will be like for Serena Williams? Will she enjoy it? Or will there be tension and high pressure on her?
It's a good question, that of course we don't know the answer to. I would say both. Hopefully she'll enjoy it. Serena is like Roger - she's not going there to lose first round. She's played four matches and lost three of them, so that's not what Serena wants. With all due respect to Cincinnati and Toronto, she wants to try to do something at the open. That's what matters.

I think that she realised, “look, I've got to get out in the court, feel it, go through those emotions that you feel on a court so that by the time I get to New York, I'll be at least somewhat comfortable with where I'm at, and I can do my thing.” Right now, it seems like the things that she did but the younger players are sticking with her now thinking “maybe she's not moving quite as well, now the pressure is not quite the same.” So that's something she's going to have to overcome as well as being consistently in points.

But the bottom line is that people are going to be pulling for herabig time. She will be in the night matches and should probably play night every time as long as she's in the tournament - and they're going to be pulling for her, so it would be nice to see her make some type of nice run.

How hard do you think it is for the next generation to follow up on the legendary players like Serena Williams and the Big Three? Who do you see as the next big stars?
As you can imagine we've been wondering about this for quite a few years. This is not the first time there's been a press conference where it's like “who's going to be the guy when the Big Three are not winning?” It’s unbelievable, in a way, what we're watching so we're almost taking something for granted that I would have told you 10 years ago would have been impossible. So my answer would be the same as I don't see any way that any of these guys will come anywhere near what we've just watched.

I think you're going to see an assortment of guys. Right now, I don't see any one guy, maybe Alcaraz can jump through all these people but you know he's not a big, big guy - he's an unbelievable athlete but he's you know six feet. If you have to play these big guys – the Zverev’s of the world, Medvedev, they are all six foot six. A lot of them guys have big serves and it just wears on you mentally, I believe. That's an issue that will make it more difficult for these young guys to dominate.

What I think we're going to see is, a little bit more like the women, where it's just going to be a lot of players winning a couple. At some point, someone who will stand out, it looked like Medvedev a year ago now. I don't know what's going on, is the war is affecting him? Who knows exactly what's going on there? He seems to maybe have slipped a little, but you'd still put him as the favourite here compared to the other guys.

Look what just happened, Coric looked better than anybody to me [in Cincinnati]. Physically, he looked like he was a level above what I'd seen from most of the players. Why not put him in as well? He's one of the guys that could win the US Open. To me, it's become much more wide open, especially (since unless something's changed when I woke up this morning) Novak's not playing. I hope something's changed, but I don't think it has. Rafa is coming off an injury. Kyrgios could potentially be that guy if he is committed, but you know it's the old story. So, it's hard to say right now.

What do you make of Iga Swiatek at the moment? Is she in a crisis?
Well, I wouldn't say it's a crisis but I think obviously her best surface is clay, I think that she's starting to be more and more effective and learning on the hardcourts. I think that I remember, and I'm not going to compare me and Iga, but when you first get that number one ranking, then the way the other players look at you is different. All of a sudden when you are number one, you have a big target on you. The players try harder, and it just feels like everyone looks at you more differently. That's an adjustment that she's had to have made and initially she did incredible  - almost too well, she won 35 matches in a row or something – it was like she's never going to lose again!

That build up culminated at Wimbledon, where she's not quite figured out how to play her best maybe on that surface and I think the pressure got to her. She's a human being, she's young, she's just coming into her own, she's done an incredible job. But I think that she's going to have to figure out a way along with her team to adapt to whatever situation is necessary.

She has been complaining about the balls, “why are the balls different in the States?”, maybe that's just letting out some nerves. Maybe there's some truth to that, maybe the balls are a little bit lighter, maybe she doesn't like that. But whatever it is, she's got to come to grips with it because she's still obviously one of the favourites, or the favourite, even though she hasn't done well, she's still going to be number one seed and people are going to expect you to do well.

She's an incredible athlete and I believe that she'll figure it out and she'll win Majors. I believe she'll win some on a faster hard court. I don't think that she's only going to win on clay.

What are your thoughts on Casper Ruud? Can he build on the experiences he had in Paris earlier this year?
With things being more open and unpredictable there's an opening for a number of players, including Casper Ruud. It's safe to say that he's been trying to figure out how best to perform on a hard court. He's tried to beef up his serve, he serves bigger. He's learning pretty well how to play, he's not a big guy and he's trying to play big time tennis. I think his best serve is when he becomes consistent, just get every ball back, take the chance when he can - it's easy for me to say, I'm watching them from afar.

I think he's done a great job, being able to finally come into his own and get to a finals of the French Open. But obviously, now all of a sudden, people are going to think he’s a better win - he's in the top five or six players so the pressure is ramped up. He's had a couple of pretty good results, but not knocking them dead since then. He didn't do much on the grass. I think he got to the semis in Montreal.

I think right now the players are sort of trying to find their pecking order in a way at each event so it's pretty open. Zverev’s not playing, Roger hasn't played, Novak looks like he's not going to play. So this has opened the door for a guy like Ruud, potentially. There's 10-15 guys that could break through and get to the end of this tournament.

Do you think Rafa Nadal is the favourite to finish the year as world number one?
Yes, I do think he is the favourite, absolutely. I would be surprised if he doesn't. Especially, as it turned out, it would have helped if there was points at Wimbledon for him. But it hurt people like Novak and other players that had done well the previous year.

He's in a great position to do that, which is amazing considering that he didn't play for six months before that. Rafa does things that you can’t believe that it happened which is why he's considered the best and up there with the all-time greatest players - you never know what to expect.

He's he didn't play the semis at Wimbledon. He lost against Coric in Cincinnati but Coric went on to win the whole thing so it doesn't look so bad right now. You know that what he cares about is the US Open. With all due respect to Cincinnati, he wasn't too worried about that so at least he got on the court again. I don't even know if it's possible right now to catch him but it would seem very surprising if he wasn't number one.\

John McEnroe will be working as an expert for Warner Bros. Discovery's coverage of the US Open, which starts on Monday 29 August. Watch the US Open LIVE across Europe (ex UK&Ire) on discovery+, Eurosport and Eurosport App.