Rafael Nadal’s tuneup for the U.S. Open didn’t go as planned. Nadal lost his opening match at the Western & Southern Open in Mason, Ohio, falling to Croatia’s Borna Coric 7–6 (9), 4–6, 6–3 on Wednesday in second-round action. Nadal, the reigning French Open champion, received a first-round bye as the tournament’s second seed. The…