One has been here before, but not for six years. The other is experiencing this for the very first time. World No. 1s Rafael Nadal and Karolina Pliskova headline the seeds for the 2017 US Open. For Nadal, it is his third time seeded No. 1 at the US Open, following 2008 and 2010, when he won the first of his two championships in New York. (The other came in 2013.) Pliskova is the top seed at a major for the first time after claiming the No. 1 spot in the WTA rankings s at Wimbledon. Last year’s US Open runner-up is the fourth different women’s No. 1 seed in Flushing Meadows in the past eight years. As the top seeds, Nadal and Pliskova will be placed at the opposite end of the draw to No. 2 seeds Andy Murray and Simona Halep and therefore would not meet their closest rivals before the finals. No seed can meet another seed until the third round, and no Top 8 seed can meet another Top 8 seed before the quarterfinals. On the men’s side, world No. 33 Diego Schwartzman, No. 34 Adrian Manna