World number one Simona Halep called her own performance "unprofessional" after she crashed out of Wimbledon.
The top seed fell to a stunning third-round defeat against world number 48 Hsieh Su-wei as the shocks kept coming in the women's singles.
Halep was leading 5-2 in the final set and had a match point, only to crumble to a 3-6 6-4 7-5 loss on Court One.
The Romanian fears she will not challenge at Wimbledon until she gets to grips with the grass.
Halep, who won the French Open on her preferred clay surface last month, said: "The ball does not bounce the same two times in a row.
"It's really tough to stay low, to play every ball, to actually expect nothing because you never know where the ball is bouncing and where it is coming. It's always a big challenge to play on a grass court.
"I cannot play my best tennis here, but I hope to improve more for the next years, to have a better result in the future.
"The match was very unprofessional for me. But I am too tired. I will not find excuses about this match, she deserved to win. But still I'm sad about myself."
Hsieh, of Taiwan, put her success down to the traditional Wimbledon diet.
"This year I tried to enjoy it more," she said. "Not just tennis. I enjoy the food, the strawberries and cream, the lobster.
"But when you play singles and doubles I need to find the time to run out to get the food."
Halep's defeat means nine of the top 10 women's seeds have been knocked out in the first week - leaving seventh seed Karolina Pliskova as the highest-ranked player.
The path looks increasingly clear for 36-year-old Serena Williams to challenge for an eighth Wimbledon title in only her fourth event since giving birth last September.
More seeds were scattered around SW19 as Belgium's Alison Van Uytvanck, who took the scalp of defending champion Garbine Muguruza in the second round, struck again.
The 24-year-old reached the fourth round of a grand slam for the first time by beating 28th seed Anett Kontaveit of Estonia 6-2 6-3.
Next up for is Van Uytvanck will be 14th seed Daria Kasatkina, the Russian beating 17th-seeded Australian Ashleigh Barty 7-5 6-3 on Court Three.
Elise Mertens, seeded 15th, was knocked out 6-2 6-2 by Johanna Konta's conqueror Dominica Cibulkova.
Cibulkova was denied a place on the list of seeds to accommodate Williams, a decision which seems to have motivated the Slovakian, who will now face Hsieh for a place in the quarter-finals.
Australian 26th seed Daria Gavrilova crashed out 6-3 6-1 to Aliaksandra Sasnovich of Belarus and Spain's Carla Suarez Navarro was another casualty, the 27th seed turfed out 6-1 7-6 (7/3) by Belinda Bencic of Switzerland.
Angelique Kerber, the 11th seed, beat Japan's Naomi Osaka to ensure she made it into week two.
The German, a Wimbledon finalist two years ago, was a comfortable 6-2 6-4 winner.
Jelena Ostapenko, the 2017 French Open champion, also went safely through after she swept aside Vitalia Diatchenko in straight sets.
The Latvian raced through the first set in 23 minutes and eventually ran out a comfortable 6-0 6-4 winner against the Russian.