Jack Sock retires midmatch vs. Ruben Bemelmans

Jack Sock, a 22-year-old American, is the latest victim of the heat wave that has gripped the 2015 US Open. In a dramatic moment that shook the overflow Grandstand crowd, Sock collapsed on the court Thursday afternoon early in the fourth set of his second-round match with Ruben Bemelmans. Sock was carried out of the stadium by trainers and security as fans gave him a standing ovation...The tournament saw a first-round Grand Slam record of 10 retirements, most of them heat-related.