Last year's winner Sofia Kenin and teenager Coco Gauff suffered second round eliminations at the Australian Open in Melbourne.
Kenin's title defence ended in a 6-3 6-2 loss to Estonia's Kaia Kanepi and the American fourth seed says the weight of expectation of being the title holder got to her.
"I know I couldn't really handle the pressure. I'm not obviously used to this, so right now I just got to figure out how to play at that level that I played at.
"I was obviously way too nervous. I felt like I obviously wasn't there. My head wasn't there.
“I'm not going to take any credit away from her. She played really well. She came up with some good shots. She obviously had a good plan against me.
“I had chances. I just couldn't take it. I obviously know why because, like, the nerves big-time got to me.
“I just couldn't execute my shots.”
Gauff went down on a 6-4, 6-3 scoreline to fifth seed Elina Svitolina of Ukraine.
Svitolina has twice been a quarter-finalist at the Australian Open.
Elsewhere in the women's singles, world number one Ashleigh Barty and Karolina Pliskova progressed to the last 32.
