Novak Djokovic, Roger Federer, Angelique Kerber, Maria Sharapova and Madison Keys were among the players who won their matches on the second day of the U.S. Open yesterday (August 28th), playing and sometimes struggling in brutally hot temperatures in Flushing Meadows, New York. The air temperature topped 95 degrees at its worst with humidity near 50 percent, making it feel like 105 degrees. Six players had to exit their matches, five of them due to cramps or heat exhaustion