Serena and Venus Williams last lost on the same day at a Grand Slam at Wimbledon in 2011 扁平疣

Serena's 6-2 6-2 defeat is her worst in terms of scoreline in her 16-year Grand Slam career

There was a brief moment of hope for coach Patrick Mouratoglou in the stands when his charge got a break back at 3-1 down in the second set, but a dreadful service game followed as she was broken for the fourth time to love 辦公室裝修.

The world number one looked as bemused as those watching, shaking her head and looking to the sky, while Muguruza remained impressively calm at the other end of the court.

The Venezuelan-born Barcelona resident recovered from 0-40 to move 5-1 ahead, as dark clouds gathered, before coolly serving out her first ever win over a top-five player to love.

Muguruza said: "I was thinking I have a chance. I have to play really good to win.

"There was a moment in the last games of the match, I was like, 'Oh, my God, I'm winning the set,' and then 4 1 or something like this 鑲牙.

"I was nervous, but I said, 'OK, be calm. She's also nervous. I have the opportunity, so I have to continue like this to win.'"

Serena said: "I just can't serve. I mean, my serve hasn't been good yet. I can't say this whole tournament, because my tournament didn't last long, but just in general."

Who is Muguruza?

Garbine Muguruza turned pro in 2011 and is making only her sixth Grand Slam appearance. The world number 35 reached the fourth round of this year's Australian Open, her best Grand Slam performance to date.

Asked to describe her year, she added: "My first few months I don't think have been great at all. I haven't got past the fourth round of a Grand Slam this year.

"I have a couple of words to describe it, but I think that would be really inappropriate so I'm going to leave it at that."

Venus Williams, 33, had earlier made a strong start before losing eight of nine games on her way to defeat against 19-year-old Schmiedlova on Court Philippe Chatrier.

"I felt like this was a match that I was most likely going to win," said Venus. "I don't know how Serena felt, but I'm sure she feels like that every time she goes on the court.

"So I think our expectation was to play in the next round."