Defending champion Angelique Kerber rued another below-par display after her disappointing season continued with a surprise defeat to American Coco Vandeweghe at the Australian Open on Sunday.
Kerber suffered the earliest exit by a women’s singles title-holder in Melbourne for a decade as she followed men’s top seed Sir Andy Murray out of the tournament at the fourth round.
World No35 Vandeweghe overpowered the German 6-2, 6-3 to claim the biggest win of her career and set up a quarter-final with Spain’s Garbine Muguruza.
“I was not playing good from the first point,” said Kerber, who also disappointed at warm-up events in Sydney and Brisbane earlier this month.
“It was not my day and not my match, but this is tennis, and you have good days and bad days.”
Vandeweghe, who has only reached the last eight of a grand slam once before, said she felt “like crap” and, despite a dominant performance, had not been confident.
“I guess I faked it,” she said. “I was nervous, but I had a game plan to execute and I knew that as along as I kept picking my spots, I had a chance.”
Veteran Venus Williams beat world No118 Mona Barthel of Germany 6-3, 7-5 and faces 24th seed Anastasia Pavlyuchenkova in the quarter-finals.