Russia's Ekaterina Makarova etched her name into Australian Open folklore on Monday by stunning Serena Williams 6-2 6-3 in their fourth-round match to end the American's aura of invincibility at Melbourne Park.
Williams, who twisted an ankle in the lead-up to the tournament, was slowed by injury in the 82-minute match on Rod Laver Arena but refused to blame it for her sensational loss to the Russian world number 56.
"She played really well, she went for broke on a lot of shots," Williams, a five-time Australian Open winner, told reporters.
"I made 37 errors and that pretty much told the story of the match.
"It was definitely hard moving to that (left) side ... I just did not serve well, it was just disastrous really.
"I never blame any injury I have because I feel like she played really well and deserved the win."
The 13-times Grand Slam champion was a picture of torment throughout, serving up seven double-faults and routinely pushing her ground-strokes wide.
But Makarova, the lowest-ranked player to reach the last 16, served it up to the 13-times Grand Slam champion, absorbing her firepower and returning it with interest.
The 23-year-old fired sweetly struck winners on important points and showed nerves of steel as she closed out the match on her fourth match point when 12th seed Williams, serving to stay in the match, pushed a backhand wide.
"I don't know what to say, it's an amazing feeling," Makarova said in a courtside interview after raising her arms in the air to raucous applause from the stands.
"I'm really happy that I finished in my way ... It's an unbelievable feeling."
Makarova's win snapped a 17-match winning streak at Melbourne Park for Williams, who won the 2009-10 titles but missed last year's tournament due to injury.
The American's last defeat at the Australian Open was by Jelena Jankovic, who beat her in the quarter-finals in 2008.
The win secured the Russian her first grand slam quarter-final, where she will face either compatriot Maria Sharapova or Germany's Sabine Lisicki, who play in the evening match.
With temperatures soaring above 30 degrees Celsius, Makarova unleashed an exquisite backhand winner to go 4-2 up in the first set against a listless Williams.
Another formidable backhand gave her the set after Williams had staved off five set points.
Williams took a 2-0 lead in the second set, but Makarova blasted yet another backhand winner to break back.
Level at 2-2, Williams double-faulted and let out a loud shriek at giving up break-point, having to restrain herself from smashing her racket on the court in anger.
The American served an ace to dig herself out of a hole, only to double-fault again to concede the decisive break and allow Makarova to seize control at 4-2.
With the crowd firmly in the Russian's corner, Makarova forced an error to bring up the first of four match points as Williams served to stay in the match.
Williams blasted an ace and two big serves to save three match points but her bid for a sixth title at Melbourne Park, was dashed when she pushed a backhand into the tramlines.
Apart from Williams's semi-final loss to unranked wildcard and eventual champion Kim Clijsters at the 2009 U.S. Open, Makarova was the lowest-ranked opponent to knock her out of a Grand Slam since 85th-ranked American Jill Craybas dumped her out of the third round at Wimbledon in 2005.
Williams said she "probably" shouldn't have played the grand slam due to her injury, but added that she was itching to get back onto the practice courts to find out what went wrong.
"That's usually how I kind of respond," she said. "I'm thinking already about practising as soon as tomorrow, you know, trying to figure - I can just think of a hundred things I can do."