This is the adidas by Stella McCartney tennis performance dress that Caroline Wozniacki is wearing at the US Open this year.
I think it is one of my favorite tennis dresses yet. It has a beautiful style, with the ribbing/ruching and mesh top, yet also seems rather practical and comfortable for actually playing tennis. I like the neutral color, so that the wearer can change her bra/shorts colors underneath the dress to give the look some variety. Also, the color doesn’t show sweat much, which is always a plus. My only real complaint about the dress, at least as worn by Caroline Wozniacki, is that I wish the dress were just a bit longer.