Groupings of four sets of four matches (16 matches make a quarter)...take the Top Half of the draw, jhl...Serena group through the grouping that begins with Zheng, and ends with Stosur. There will always be 2 seeds between 1 and 8 in a quarter, one in the first line, the other in the 16th line. So this quarter, if seeds held, would be Serena against Sam Stosur.