The 2015 US Open saw some delightful bits of action on its first day of play on Monday, 31 August. Some of the big names of the sport were in action. Day one saw a major upset in the form of Japanese, Kei Nishikori.

The Japanese tennis star, finalist at last year's edition, was sent packing from Flushing Meadows after a five set - 6-4, 3-6, 4-6, 7-6 (8-6), 6-4 - defeat at the hands of Frenchman Benoit Paire. However, normal service continued in the day's other matches, as Serena Williams, Venus Williams, Novak Djokovic and Rafael Nadal, among others, won their ties to progress to the 2nd round.

Here are some of the best moments from the first day: