She crashed out after a 6-4 6-4 defeat by Spanish world number 71 Rebeka Masarova, capping a miserable year at the Grand Slams after first-round exits at the French Open and Wimbledon and a third-round appearance at the Australian Open.
"I wouldn't say I was playing well," an emotional Sakkari told Eurosport. "If I played at least five or 10% better, I would have won that match.
"These are the matches that I have to win. I cannot lose these matches; there have been too many for my level this year, and it's unfortunate.
"I just feel like my level was and has been poor and I have to do something about it. It's not a lack of effort, for sure.
"It's very uncertain, I don't know what I am going to do, whether I am going to take a break or not."