Defending champion Angelique Kerber has been knocked out of Wimbledon in the second round after a stunning display by world number 95 Lauren Davis.
Seven-time Wimbledon champion Serena Williams recovered from being a set down to beat teenage qualifier Kaja Juvan and reach the third round.
The German, 31, could not get off court two quickly enough after a 2-6 6-2 6-1 defeat by the American, who was only in the tournament as a lucky loser.
The fifth seed saved two match points before sending a backhand into the net as the crowd watched in disbelief.
"I am so happy to win, it is almost surreal," said 25-year-old Davis.
"This means everything as it is what I work for."
Top seed Ashleigh Barty, sixth seed Petra Kvitova and Sloane Stephens, seeded ninth, made it through safely to the third round with straight-set victories.