Britain's Andy Murray said he had "not let anyone down" after losing to Japan's Kei Nishikori in the Us Open quarter-finals.
Sixth seed Nishikori won 1-6 6-4 4-6 6-1 7-5 to inflict an earliest Grand Slam defeat of the season on Murray.
The Scot, 29, finished runner-up at the Australian and French Opens before winning Wimbledon and Olympic gold.
"I tried my best. I fought as as hard as I could with what I had today," said the world number two.
"I pushed myself as hard as I could over the last few months and I'm very proud of how I've done.