Overall, women's tennis is suffering a bad period.
None of the players are finding consistent enough results, or are able to provide an entertaining game; right now the game is a bit of a mess.
Apart from a few matches, this year's US Open lacked interest, both in terms of spectacle and results with a lot of one-sided battles. Unfortunately this tournament has showed again that the level of women's tennis is going down.
In this context, and with Serena Williams out of the picture, it was not surprising to find Kim Clijsters a level above the others.
She's just playing way better tennis. Steady and aggressive, she's acts like a leader on the court.
If we forget some dreadful matches like at the Australian Open against Nadia Petrova, at Indian Wells against Alisa Kleybanova and during Wimbledon against Vera Zvonareva, Kim has had a really good season with victories in Brisbane, Miami, Cincinnati and the US Open.
She's playing an interesting game, which relies a lot on footwork with diversity in shot selection. It's a very complete game, without an outstanding weapon but also without any weak aspects.
And as she's taking the ball earlier, she hurts her opponents way more than Caroline Wozniacki or Zvonareva because she can use this speed of play to move forward.
Wozniacki was the main disappointment in New York, even if she did reach the semi-finals. She was seen as the main favourite with a three-tournament winning streak. She was the most in-shape player and had improved a lot on serve and forehand.
But she showed nothing of that against Zvonareva; those two shots imploded under attack from the Russian. Was she caught out by the pressure or, more likely, by the fatigue of a packed summer?
I was really surprised to see her play in New Haven, the week before the US Open, after she had won Copenhagen and Montreal and when it would have been the ideal time to rest and focus on the goal of winning a first Grand Slam.
The main surprise came from Zvonareva, who confirmed her Wimbledon final by getting to the same stage in New York.
For some months now she seems to have enjoyed a new dimension to her game. She's way more confident than before, she trusts her game so isn't freaking out anymore and she builds her points in a very clever way.
She knows how to play with pace, when to slow it down and how to suddenly play flat in order to disturb her opponent. She's very serious and focused so she deserves her place at the very top of the game. We're used to see her alone in the fitness room, working for hours.
We also saw some good tennis from others. Sam Stosur delivered beautifully against Elena Dementieva; she continues to improve and time is working for her - there is enough for her to build the confidence she needs.
Francesca Schiavone is always a pleasure to watch with her diversity, the way she changes pace, wrong-footing opponents and her net game. She's also always physically involved in a match, living them with a rare intensity.
And we should not forget Andrea Petkovic, who knows how to keep the audience on the edge of their seats with her thrilling matches. She won her first-round match 7-6 in the third set against Petrova, saved three match points in the second round against Bethanie Mattek-Sands before winning it 7-5 in the third set with an amazing forehand winner.
Other players had convincing performances, among them former stars Ana Ivanovic and Dominika Cibulkova.
Ivanovic started to shine again in Cincinnati and confirmed her early return to form at the US Open. Her serve is more efficient again, just like her forehand. She has also found some positive emotional comfort and now knows how to keep calm when things are not going the way she would like.
Cibulkova achieved a great US Open result after struggling for months. The former world number 13 is still very young and could have a bright future. Her footwork is amazing and should help her climb the rankings again, especially now that she's helped by Zeljko Krajan, former coach of Dinara Safina.
Two other players that are promising are Anastasia Pavlyuchenkova and Petkovic.
The young Russian went through a good summer and experienced her first fourth-round appearance in a Grand Slam. She's displaying a game that could be key to her success in the years to come.
The German has improved a lot this season, as she did in the last one. She's a beautiful player, a real athlete and such a fighter. We should hear from her again very soon.
Even if she lost in fourth round, compared to her run to the semis last year Belgian Yanina Wickmayer also has everything it takes to shine in the future.