What does it mean to win a calendar Grand Slam in tennis?
I thought I would win two Grand Slams. I won three out of four, but not in a year, not in a calendar year. I fully realise how difficult it is to have this pressure of winning four major tournaments in the same year. Especially if, obviously, Novak Djokovic here is preparing for the Grand Slams. And so the pressure is maybe even greater despite the experience, but he wants to be there in those moments.

That means the preparation is going to be even more thorough. But really, for me, what I remember is the management of the pressure in relation to four major tournaments. It's a long fortnight. Physically, the five-set matches, we know that it's tiring. He started the year at the Australian Open in difficult conditions. I find it quite impressive. There's still a long way to go. It will be long, but it's so rare that you can't trivialise it. Obviously, there will be a lot of attention on this US Open which is going to be very special.

Can you compare this achievement with Rod Laver’s?
It's the eternal battle of comparing eras and comparing what Rafa did at the French Open to Roger's career or his titles at Wimbledon. Like it or not, Novak Djokovic remains a bit in the shadow and will probably never really be the hero or idol that Roger Federer and Rafael Nadal are. But what he is achieving in an era where tennis is at a really exceptional level, and particularly physically, the schedules are much more demanding than they were in the past – it is incredible.

We mustn't forget the Covid period. For a lot of players, you have to be very strong in your head at this time. I think you really have to be very, very strong. I don't know how I could have experienced things. All that makes it a major achievement. Today, I still find it difficult to compare eras, but we're in an era of men's tennis, and it's going to be difficult to know better in the decades to come.

Is it a matter time before Novak Djokovic leads the GOAT race?
I think Novak Djokovic is the one who's going to hold the records very quickly and I think it's going to be very, very difficult to go after them. A lot has happened in the last year. His disqualification at the US Open last year, a stinging defeat in the final at the French Open, and after that at the Australian Open, there's a lot at stake because there's the ego of the champion where he wants to win Grand Slams.

He wants to get closer, and he did something very, very strong at the Australian Open. Obviously, for me, it's all about that match against Nadal at the French Open, where he came back from two sets down. You can feel for Novak Djokovic, everything is always a little bit complicated, but in the end, very regularly, he comes through.

I'm not going to say that other people aren't competitors. You don't win 20 Grand Slams in your career... They are huge champions and you can't compare all three of them. But if we're talking about records, I think Novak Djokovic is going to be in the best position very soon and it might be impossible to go after.

Is there anyone from the new generation that you see as more dangerous for Novak at the US Open?
I think Zverev has evolved a lot. He's made some progress, obviously mentally. I think that beating Novak at the Olympics and going to win a big title. I think it's going to be a big moment in his career anyway. Is that going to be enough?

Last year he was very, very close to being able to win the US Open in different conditions. I think he's a guy who's evolving his game. He beat Novak at an important moment. It wasn't a Grand Slam and so that's what we're going to question.

We're obviously going to talk about Medvedev, Stefanos Tsitsipas, who was in a position to win his first Grand Slam and who also faded a bit. 

Novak has a psychological advantage over all these players, but the gap is closing. I'll never forget what he said at the Australian Open when we were talking about the young generation. He said, "Yes, it's good, they're here, they're growing, but they're not winning much.

I thought he was quite right in what he said, it could have been taken as pretentious. On the other hand, what he has achieved, you can't take that away from him. And he proved once again that the young generation still has to work and take steps that are still a bit timid in these important moments. They're still a bit shy, Tsitsipas, he remained a bit shy.

They have everything in their hands to be able to make the difference against a player like that. So, we're going to talk a lot about this quest for the Grand Slam. It's going to be a lot of that. It's going to be part of all the questions. It's going to be part of all the questions, all the press conferences, and everybody's going to have to deal with it as well. So it's going to be interesting.

I think it's really going to be an exciting, unique edition and I think we're going to see some turnarounds. Anyway, lots of emotions and we're really looking forward to it.

Who is going to do it?
My answer can't be quick. Frankly, there's something that tells me but yes, because it's Novak Djokovic. I have a thing that says no because it's Novak Djokovic and he's a nervous boy. So what? He's been able to master all that obviously throughout his career because he's a man of challenge. And so, you almost want to say to yourself that it's impossible for him to miss out today. But this is a big question today and I don't have the answer...

Justine Henin will providing expert analysis for Eurosport and discovery+ (selected markets) during the US Open across Europe except UK & Ireland, which starts on Monday 30 August.