It has taken her a while to grow into the role, but Simona Halep is definitely looking and playing like the World No.1.

With just over a week to go until the US Open, there is a new confidence and a new attitude now to Halep, who won the Montreal title last weekend, and who seems to be saying to the rest of the WTA tour: "I'm No.1 and you're going to have to try to knock me off my perch."

Read more: Navratilova: Halep must step outside of her comfort zone

Winning a first major at the French Open brought about this change in Halep. Perhaps that change wasn't evident at Wimbledon, which came quickly after Paris, and where she lost in the third round, but now her victory in Paris has sunk in, and she can think to herself: "I've been there and done that." The majors are more important now than they were when I was playing. Now you're not a legitimate No.1 in anyone's eyes unless you have won a major somewhere along the way. So Halep has cemented her place at the top and taken a big monkey off her back.

She no longer has to answer that question: "When are you going to win a major?" And what was a negative - and something she was reminded of almost every day, when doing media interviews - has turned into a positive.

I think Halep's new confidence and attitude are going to make her more proactive during rallies, and that's going to help her to play better on the US Open hard courts. For Halep, there has always been the battle of whether to just stay in the point or to be more proactive. Now she's the one taking the initiative in rallies. With her confidence, a faster court could actually be to her advantage. She can still defend well enough, but her more aggressive shots will pay off better at the US Open than they did on the French Open clay.

For Halep, and for anyone else contending for the US Open title this summer, it's important to embrace the tournament's personality. Every Grand Slam has a different personality to it, and you have to know what it is and you have to embrace it and you'll be OK. The noise, the distractions and everything else at the US Open, they're the same for everybody. As long as you don't fight these and you adapt to them, you'll be just fine. You just need to quickly deal with those elements, make sure you don't lose any energy thinking about them and just play ball.

Read more: The story of Montreal - Halep outlasts Stephens in final

I think that Sloane Stephens - the defending champion at the US Open, and a runner-up to Halep in Montreal - could do with getting a little bit fitter. As well as she played against Halep, she looked a bit tired in the third set.

As things stand now, when Stephens plays Halep, it looks to me like she needs to beat her in two sets. Sloane has faded in the third set both times she has played Halep this season. So I think she needs to be in slightly better shape for those more physical matches. It shows up the most with balls that are hit right at her because it takes energy to get out of the way. It's more difficult to get out of the way of a ball than to step into a ball. And when you get tired, you just can't do it well enough without making too many errors along the way.

Stephens was repeatedly struggling with those balls hit right at her. She was dumping them in the net because first you have to step away from the ball and then step into it when you’re hitting. If you don’t step into it, it’s all arm when swinging and that’s when the mistakes pile on. So it’s that simple - better fitness.

But better fitness is a nice problem to have because it's an easy fix - you just have to put in the work, that's all.

Winning Wimbledon has had a huge effect on Angelique Kerber. She has grown in confidence and now realises she can be World No.1 at the end of the year. That's a pretty big carrot. The way she plays, her game is well suited to the US Open, as she can defend but she can also hit that flat ball that penetrates the court. Kerber was the champion in 2016, and she's going to be a huge threat in New York again this summer.