All negatives for Azarenka
Victoria Azarenka admitted "pretty much everything" had gone wrong as she crashed out of the French Open in the fourth round on Sunday.
The 22-year-old went on a 26-match winning streak at the start of 2012, including picking up her first grand slam title at the Australian Open, but she has struggled to find her form all week.
Azarenka almost went out in the first round, fighting back from a set and 4-0 down against Alberta Brianti, but today she could not recover and was beaten 6-2 7-6 (7/4) by the 15th seed.
The Belarusian said: "I don't know how to describe my performance really today. It wasn't satisfying at all. It wasn't satisfying being out there playing that way.
"But I guess it happens. I don't know even what to find positive in my performance today. Maybe in a few hours I'll find something that I can be happy with."
Despite being only 5ft 3in tall, nine inches shorter than Azarenka, Cibulkova is a talented and feisty competitor and she had far too much for her opponent in the first set.
Azarenka had fought back from significant deficits in her last two matches against the Slovakian, who she had lost only once to in eight previous meetings.
And from 4-2 down in the second set she ended up serving for it only for Cibulkova to break back and dominate the tie-break, clinching victory on her second match point.
Azarenka said: "She's definitely a good player. I think she plays much better against the top players than maybe a little bit lower-ranked players. She really has that desire. I don't know what motivates her to play that way.
"She's a dangerous opponent. She had big wins before, and it was no surprise that she was going to be playing well today.
"(Against Cibulkova) before I was at least making something happen myself. Today I couldn't do it. It was just not going for me. I tried everything. All I could hope for was her mistakes."
Azarenka admitted she is mentally jaded after a demanding season and she is not planning to play any grass-court tournaments in the build-up to Wimbledon.
"There has been a lot of tennis for me in the last five months," said the 22-year-old.
"I haven't been home in a while, and it's something that I need just to get rested mentally, definitely, and just to get out of the tennis field a little bit. And once I have my passion and desire back on the court, I'll be on the grass."
Cibulkova's best performance in a slam came here in 2009, when she reached the semi-finals, but she admitted the losses to Azarenka had weighed on her mind.
"You can't be human if you weren't thinking about that," she said. "Because this year in Miami I was 6-1 5-2 up against her. And last year in Miami it was the same.
"Today it happened the same when I was 4-2 up. And that's why I got a little bit, not nervous, but not going for my shots anymore.
"But today it was a great thing that I managed to go through these emotions. She was 6-5 up, and I said, 'Hey, come on, you have to play your game again and just make it'.
"And for the tie-break I'm very, very proud of myself that I was still going for my shots, and I just made it because she would never give me the match."
In the last eight Cibulkova will play sixth seed Sam Stosur, who is now a hot favourite to reach her second final at Roland Garros.
The Australian, who lost the showpiece to Francesca Schiavone in 2010, recovered from 5-3 down in the first set today to beat 19-year-old American Sloane Stephens 7-5 6-4.
Italy's Sara Errani is through to the quarter-finals of a second successive grand slam after putting out former French Open champion Svetlana Kuznetsova.
Errani, the 21st seed , was too consistent and too smart for 2009 winner Kuznetsova, who made far too many errors in the cold and windy conditions, particularly in the first set, before going down 6-0 7-5.
The Russian has had a poor season, and she said: "The first set was just horrible. Today the weather was so bad. I felt cold during the whole match.
"It's the best I've seen Sara play. Her game is very good on clay. I'm far away from my best form yet."
The 21st seed has had a superb season, winning three titles, all on clay, as well as making the last eight at the Australian Open, and in the quarter-finals here she will play 10th seed Angelique Kerber.
German Kerber, who was outside the top 100 before reaching the semi-finals of the US Open last year, beat Croatia's Petra Martic 6-3 7-5.