But the 24-year-old from Troisdorf in Germany still smiles at the memory of that fourth-round win. There's no better scalp in tennis than the woman who holds 57 WTA titles including 17 in grand slam singles. "Serena's No 1 in the world, so she's the best player," Lisicki said after touching down in Brisbane, where she could again face the imposing frame of the 32-year-old from Florida at the Brisbane International starting on Sunday. "I have respect for her, but as soon as I'm on the court I just want to win."
Not many people beat Williams in a grand slam. She's played in 49 of them and reached the quarter-finals at least 37 times.
"It gave me a lot of confidence to beat Serena, especially on grass, where she was the favourite," Lisicki said.
"I work just as hard so you wait for those moments for the work to pay off."
Another of those entered for Brisbane is Andrea Petkovic, who has met Williams only once (lost in Rome in 2010) but has been a long-time fan. "When Serena won her first slam I was not playing yet on the women's tour," Petkovic said. "She was my idol and I really liked her and admired her because I thought she brought something new to tennis.
"She brought power and entertainment. She was rebellious to me somehow, and I really liked that," the 26-year-old said.
"So I grew up with her and Steffi (Graf) as my idols. Now being able to play her and see her compete that well again after all her injuries and all she's been through, it's so inspiring.
"For all of us it makes us work hard to try and give our best to try to beat her. For her also that's probably what keeps her going, because she knows everyone wants to beat her.
"She's done an incredible job and is definitely an icon in tennis."
Neither Lisicki nor Petkovic said they were intimidated by Williams. They fully accept she is the one to beat and they acknowledge the privilege of playing against someone who will likely be recognised as the best female tennis player in history.
"Serena is still the one," Lisicki said. "You have to play your best tennis to get near to beating her. But once you do that, anything is possible."
As Germans, Petkovic and Lisicki have grown up in the shadow of Graf -- the holder of 22 grand slam singles. "We don't know any different because Steffi won so many grand slams and was such a great player that everything has been stacked so high," said world No 15 Lisicki.
She lost second round in Brisbane in January and first round in Melbourne, so she has everything to gain in Australia this time around. "Yes, it is time for the top 10. I don't have any points to defend in Melbourne and really, for the first four months I only have points to gain," she said.
Photo Gallery of Sabine Lisicki: