Defending champion Andy Murray looked to his recent successes at Grand Slams after losing to Stanislas Wawrinka in the quarter-finals of the US Open.
The Briton, who won his second major title at Wimbledon two months ago, had reached the final at his last four Grand Slam tournaments.
"I don't know if I'm meant to win every Grand Slam I play or be in the final," said Murray, 26. "It's just very, very difficult just now. With the guys around us, it's very challenging.
"I have played my best tennis in the Slams the last two, three years. I lost today in straight sets, so that's disappointing. I would have liked to have gone further but I can't complain.
"If someone told me before the US Open last year I would have been here as defending champion, having won Wimbledon and Olympic gold, I would have taken that 100%.
"So I'm disappointed, but the year as a whole has been a good one."
Murray admitted there had been something of a comedown after the high of winning Wimbledon, but insisted he had been focused and well prepared in New York.
"When you work hard for something for a lot of years, it's going to take a bit of time to really fire yourself up and get yourself training 110%," said the Scot.
"That's something that I think is kind of natural after what happened at Wimbledon.
"But I have been here nearly three weeks now. I practised a lot, and played quite a lot of matches as well, so I gave myself a chance to do well because I prepared properly."
The world number three struggled to get going at Flushing Meadows this year, and an unusual schedule and variable weather did not help.
"You guys can see for yourself how the schedule worked out," said Murray, who had to wait until the night session on day three to play his first-round match.
"When you play the first round over three days, it's tough."
Murray's next event is Great Britain's Davis Cup tie in Croatia from 13-15 September, which will involve a change of surface.
"I need to take a few days' rest and then get practising on the clay courts and hopefully we can win the match," he said.
Ninth seed Wawrinka is through to his first Grand Slam semi-final and said he was most proud of being able to handle the pressure.
"Normally I can be a little bit nervous and I can lose a few games because of that, but today I was just focused on my game," said the 28-year-old from Switzerland.
"It was really windy, not easy conditions, but my plan was to push him to be aggressive because I know that Andy can be a little bit too defensive.
"I like it when he's far back from the baseline and today I did it well."
Wawrinka added that compatriot and five-time US Open champion Roger Federer had texted him after the match, saying: "He told me congrats, that's for sure."