Petra Kvitova of the Czech Republic comments on her play at the WTA Championships in Istanbul, Turkey, which runs from Oct 22 until Oct 27:

I feel really good (to win the first match against Agnieszka Radwanska of Poland). I mean, the first match is always tough in the Championships, and in other tournaments, too.

I was nervous before the match because I recalled last year,when I lost to her (in) the first match of the Championships, so I'm really glad that I won today.

I finished quite late today, and I'm glad that I have tomorrow off so that I can practice a bit, rest in the afternoon and have more energy for the next match.

Serena is a big favorite of our group, and she played well today, starting pretty aggressively. For me, it's a big challenge to face her, so I'm looking forward to the match.

I would give a "6" for my performance this year because it has been full of ups and downs I had a few difficult times this season; it is always tough mentally. I lost my confidence a little bit. It was tough, but I tried to be as positive as I could be. I worked very hard, and I have great people who always trust me.

As for next year, I will try to return to the top five. I have a new fitness coach, so I am looking forward to the preparation .

Fans in Istanbul are incredible. I remember in 2011 when I was here for the first time, people didn't come a lot. It was full attendance in the finals in 2011, and last year it was full for every match. I think Turkish people like to watch tennis.

One of this year's great memories was that I took a photo with Li Na before the draw ceremony. We are close friends. She is nice, and we always have lots of fun. We understand each other well.

I know that next year the Pan Pacific tournament will be in Wuhan, which is Li Na's hometown. I think there will be huge support for Li Na, so it is going to be tough to play her there.

Xiexie!