Andy Murray "proud" despite US Open exit at hands of Kei Nishikori

World number two Andy Murray has insisted that he remains "proud" of his achievements despite exiting the US Open at the quarter-final stage after being beaten by Japan's Kei Nishikori.

Murray, who claimed an Olympic gold and a second Wimbledon title earlier in the summer, suffered his earliest Grand Slam defeat of the season following a 1-6 6-4 4-6 6-1 7-5 loss on Wednesday evening.

"I tried my best. I fought as as hard as I could with what I had today," said Murray, according to BBC Sport.

"I pushed myself as hard as I could over the last few months and I'm very proud of how I've done."

The defeat was just the second that Murray has suffered in 28 matches.