MELBOURNE, Australia (AP) Fireworks lit up the sky above Rod Laver Arena the moment Venus Williams completed her fourth-round win at the Australian Open on Monday night.
It's been that kind of tournament so far for the 34-year-old, seven-time Grand Slam winner. Williams advanced to her first quarterfinal in a major since Wimbledon in 2010 and she'll be joined by her younger sister, Serena, in the final eight.
As multi-colored pinwheels and other fireworks celebrating the Australia Day holiday cascaded from the sky, Venus took time on court to credit Serena for her support and inspiration.
In 2011, Venus was diagnosed with the energy-sapping Sjogren's syndrome, a major reason for her absence from the late stages of big tournaments - until now.
"Definitely my sister Serena, she's just the ultimate champion, and definitely a lot of inspiration from all my fans who have stayed behind me through thick and thin," Venus said.
On the men's side, No. 1-seeded Novak Djokovic , defending champion Stan Wawrinka, U.S. Open runner-up Kei Nishikori and Canadian Milos Raonic won their fourth-round matches. That sets up a pair of compelling quarterfinals: Djokovic vs. Raonic, and Wawrinka vs. Nishikori.
Venus Williams, asked if her 6-3, 2-6, 6-1 win over Agnieszka Radwanska was her biggest in a while, said "from the outside looking in, I guess it could be like that.
"(But) I feel like I've been here before so it's not like I'm jumping up and down for joy."
Venus will next face Madison Keys, a 19-year-old American who was inspired to play tennis by watching the Williams sisters.
"It's definitely been an experience, really playing well, kind of living up to what people have been saying," Keys said. "I'm just really happy that it's finally here and that I'm doing so well."
Serena Williams had a 2-6, 6-3, 6-2 win over Garbine Muguruza, motivated by a loss to the Spanish player at the 2014 French Open.
"She made me play a lot better," Serena Williams said. "I had to play the best match of the tournament or else I was going to be out."
The five-time Australian Open winner next faces Dominika Cibulkova, who beat two-time champion Victoria Azarenka 6-2, 3-6, 6-3. Keys advanced to her first Grand Slam quarterfinal with a 6-2, 6-4 win over good friend and fellow American Madison Brengle.
Serena Williams had difficulty breathing at times Monday and coughed throughout.
"When I got down, I was thinking, `What can I do now?'" Williams said. "Whatever happens, I thought, I've won this five times."
Looking for No. 6, she'll need to get past Cibulkova, who hit 44 winners and broke former No. 1-ranked Azarenka's serve seven times. The No. 10-ranked Cibulkova lost in the final here last year to the now-retired Li Na.
Wawrinka advanced by beating Guillermo Garcia-Lopez 7-6 (2), 6-4, 4-6, 7-6 (8) and No. 8 Raonic posted a 6-4, 4-6, 6-3, 6-7 (7), 6-3 win over No. 12 Feliciano Lopez. Spurred on by hundreds of flag-waving Japanese supporters at Rod Laver Arena, No. 5-ranked Nishikori had little trouble in a 6-3, 6-3, 6-3 win over No. 9 David Ferrer.
Wawrinka saved four set points in the last tiebreaker, while trailing 6-2, and then saved a fifth before clinching it on his second match point.
The win helped Wawrinka gain some payback against Garcia-Lopez for an unwanted record. Last year at the French Open, the Spanish player beat him in the first round, making Wawrinka the first first-time major winner to lose his opening match at the subsequent Grand Slam since Lleyton Hewitt lost at the 2002 Australian Open after winning the 2001 U.S. Open.
"I knew once I came back to 6-5, he'd been getting nervous," Wawrinka said of the tiebreaker. "I hit a passing shot along the line. They always know I go along the line."
After Venus' match on Rod Laver, Djokovic beat Gilles Muller 6-4, 7-5, 7-5 to advance to his 23rd consecutive quarterfinal in a Grand Slam tournament, a feat which appears to dwarf Venus Williams' first in nearly five years - unless you're Venus.
"Any win gives you that rush, whether it's a first round or the last round," Williams says. "I'll be back out on Wednesday trying to play my heart out again."