World No. 1 Caroline Wozniacki still won’t reveal the identity of her mystery coach, but does say that she wouldn’t mind matching the feats of her boyfriend, U.S. Open gold champion Rory McIlroy.

"Yeah, well, you know, definitely trying to keep up," she said. "I'll definitely do my best, but I still have six tough matches to go, so it will not be easy. He has something I'm looking for and I have something he's looking for. He wants to be No. 1. So it's good to have something on each other."

Wozniacki and her father-coach, Piotr, have brought in another coach to help her, but he does not want to be identified, presumably because he is working with another player or a tennis federation. However, he is watching tapes of her matches. "He's been watching me play and telling me a few things,” she said. "It's good. It's working well."