Less than 48 hours after sending world number one Iga Swiatek crashing out of the tournament, the Latvian 20th seed found herself heading for the exits after a 6-0, 6-2 drubbing.
But Ostapenko was unhappy at tournament scheduling that left her having to face a noon quarter-final in searing heat on the Arthur Ashe Stadium court so soon after her fourth-round win.
"Today was not really good match from me," Ostapenko said.
"I think it's really hard to recover from those night matches because after beating world No. 1, I went to sleep at, like, 5:00 in the morning.
"You sleep for, I don't know, maybe like seven, eight hours, but you completely don't recover.
"Yesterday the whole day I felt very low energy. I thought today I was going to wake up and feel better. But honestly, I didn't really feel much better."
"I think it's a little bit crazy," she added.
"If I play a match, a late-night session, then I suppose in one day I have to play at least at the same time or later on because you don't really have much time to recover."
Ostapenko said tournament officials had led her to believe she would be given a later start on Tuesday following her win over Swiatek, which wrapped up just minutes before midnight on Sunday.
"I was pretty sure I'm gonna play at night session because that's what they told me," Ostapenko said.
"When I saw the schedule I was a little bit surprised, not in a really good way."
Meanwhile, Ostapenko said while she hadn't been bothered by the heat, the bright sunshine on the court had caused her problems.
"It was very hard to see the ball because half of the court was in the shadow and half was in the sun," she said.
"I felt like I was reacting too late because of the shadow."
