Video: Williams, Ivanovic, Pennetta and Errani on Thursday's action

Reaction after the early action at the US Open on Thursday.

Serena Williams (on the last three remaining Americans all in her corner of the draw)
“You have to be ready for everything and every part. We’ll see what happens. I mean, all of them have been playing well. Sloane plays excellent, and Jamie has been playing really well. Hopefully I can just try to keep up.”

Ana Ivanovic (on her continuing improvement)
“Well, I think I still have a lot of work to be done, in all honesty. Like you said, I have been there so I know how it feels. It’s very tough competition out there. I have to be more consistent, you know, and on higher level. It’s no secret in that. I have to, you know, start winning the matches that I had against Azarenka and Li Na in last couple of tournaments, these are the matches I need to win in order to get back there. It’s still a long way. It’s still also to enjoy the process of getting back there. That’s what I’m realising. I really put my head down and I want to achieve that.”

Flavia Pennetta (on her win over Sara Errani)
“For me this tournament is really special, you know. I have really good memories here and I always enjoy to play the US Open and I think today was one of my best matches. I’m really happy to be here again.”

Sara Errani (admitting the pressure was too much for her in her loss to Flavia Pannetta)
“I don’t know why. I mean, I think is the pressure. Everything is very difficult for me. That’s it.”