Roger Federer admits he feared he would struggle against Italy's Andreas Seppi in the Australian Open.
The four-time champion lost 6-4 7-6 (7-5) 4-6 7-6 (7-5) - the first time since 2003 he hasn't reached the last four.
The Swiss player, 33, had won all 10 of his previous matches against Seppi, the world number 46.
"I felt for some reason yesterday and this morning it was not going to be very simple today," he said. "Even in practice I still felt the same."
Federer added: "I was just hoping it was one of those feelings you sometimes have and it's totally not true and you just come out and you play a routine match."
Federer has won only one of his 17 Grand Slam titles in the last five years, at Wimbledon in 2012, but said his unease before the match was a familiar feeling.
"This is a feeling I've had for 15 years," he said. "To me, I don't read anything into that. It's just not the best feeling to have.
"It's not like I'm playing shocking or I'm feeling shocking. It's like one of those things you look back and maybe think, 'Yeah, I didn't feel so good'.
"But if you win, you never even question it. If I were you, I wouldn't read very much into that."
"Clearly I'll have a look at it, but I don't think I did anything wrong honestly," he said.
"I wanted to go to India. I wanted to go back to Switzerland for Christmas. I practised as hard as I possibly could. I can't do more than that.
"Sure, the year ended late, but one week later than normal. At the end of the day, honestly I'm confident that what I did was the right thing."
Federer now plans to rest before returning to action in Dubai next month.