U.S. Open Tennis 2014: Novak Djokovic Loses to Kei Nishikori in Semifinals, Blames Heat? [VIDEO]

Top-ranked Novak Djokovic was stunned in the semifinals of the U.S. Open, losing to Japan's Kei Nishikori 6-4, 1-6, 7-6 (4), 6-3 on Saturday. Nishikori became the first man to reach a Grand Slam final.