Serena Williams walked on court for her first-round match at the U.S. Open Tuesday evening in a dark blue dress with sharp, neon-yellow triangular stripes down the middle. Her game was a lot like those stripes, clean and sharp, with none of the roughness around the edges that we often associate with Serena as she plays her way into form over the course of the first week at a Grand Slam. On this night, she was coldly efficient rather than overwhelming. Williams hit just 16 winners against nine unforced errors; very clean, but not head-turning, numbers for her. Yet she won 50 points and lost just 24, and converted on six of her seven break points, in her 6-1, 6-1 brush-off of fellow Californian Coco Vandeweghe.