Victoria Azarenka lamented a "flat" display in her below-par performance and surprise loss to Angelique Kerber at the Australian Open on Wednesday.
The Belarusian two-time grand slam champion slumped to a 6-3 7-5 defeat in the quarter-final on Rod Laver Arena.
Azarenka started poorly before getting into the match in the second set, only to lose five consecutive games from 5-2 up.
The 26-year-old said there were several aspects of her game that were below expectations after she committed 33 unforced errors in her first loss to the German.
"I think I was a little bit too flat today. I obviously didn't start great. For me personally, it was a little bit 10 per cent not enough of everything," Azarenka said.
"My footwork didn't have enough. My shots didn't have enough. I felt I had too many unforced errors in the key moments.
"I created a lot of opportunities, but then I was not enough in my opportunities. I didn't take them. I had plenty.
"That's not going to win matches in quarter-finals. You have to bring it, and I didn't."
Azarenka had not lost a set this year heading into the last-eight clash, but quickly found herself fighting back from 4-0 down.
But the two-time Australian Open winner said she felt no different leading into the contest.
"I felt fine. I was thinking about it right now, if there is something I could have done differently, if there is something I've done wrong. I went through my routine," Azarenka said.
"Mentally I didn't commit myself enough today. I didn't push myself into making a difference. I was too flat."