I think Kim came back with a skill set that hasn't been seen in the WTA for a few years now. Serena was out of sorts because she has been skating by playing what passes for the top players of the WTA without having to think or work very hard to beat them. She's had some competitive matches but for the most part when she's wanted to be focused she has been and has wiped the floor with the competition. Watching that match I saw a Serena pushed out of the comfort zone she's been in for awhile. Kim can think on court. She doesn't need her hand held and she doesn't whine and have a meltdown when something in her game isn't working. What does she do? She goes to plan B. She was countering every move Serena, and before her Venus, made. I would argue that an uninjured Venus had the better chance of beating her but that's water under the bridge. Kim brings a true skill set to the court something all the cute girls who hit the ball hard don't have. Serena pretty much acknowledged this when she said afterwards that she'd be ready for her next time.