- Maria Sharpapova forced out of Brisbane International
- Right collarbone injury has not cleared up in time
- Serena Williams marches into last eight with straight sets win
- John Millman earns second round clash with Andy Murray
Maria Sharapova's preparations for the Australian Open suffered a blow when she was forced to pull out of the season opening tournament in Brisbane Tuesday with a right collarbone injury.
The World No.2 was due to play Australian wildcard Jarmila Gajdosova in the second round, but said she had "ran out of time" in her battle to recover from the problem.
"I have a bit of inflammation in my collarbone," she told the official tournament website.
The 25-year-old Russian said she had sent scans to her doctor in New York to assess the injury, which forced her out of an exhibition tournament in South Korea last week.
"He told me I couldn't really do much overhead training for about a week," revealed Sharapova.
"So to be fair, I haven't really given myself a chance to pretty much hit any serves or anything over my head. Just been practicing groundstrokes," she added.
The reigning French Open champion will also skip next week's WTA tournament in Sydney to recover in time for the start of the Australian Open on January 14.
Sharapova was also forced to pull out of last year's Brisbane tournament, but went on to reach the final of the Australian Open, where she was beaten by Victoria Azarenka of Belarus.
Azarenka is the top seed in Brisbane and will play her second round match against Sabine Lisicki of Germany Wednesday.
Gajdosova will play lucky loser Lesia Tsurenko of Ukraine, who replaces Sharapova in the draw.
In second round action Tuesday, Serena Williams needed exactly one hour to reach the quarterfinals with a crushing 6-2 6-2 win over France's Alize Cornet in the night session.
The 15-times grand slam winner was, like Sharapova, an injury doubt before the start of the season, but has shrugged off a foot problem to look in ominous early season form.
She hit 25 winners, including six aces, to overpower Cornet.
But former champion and sixth seed Petra Kvitova was sent crashing 6-4 7-5 by Russia's Anastasia Pavlyuchenkova.
Fifth-seeded Italian Sara Errani also lost in three sets to 2012 runner-up Daniela Hantuchova 4-6 6-1 7-5.
U.S. Open champion Andy Murray is the top seed in the ATP event in Brisbane and begins his campaign Thursday against qualifier John Millman
The Australian beat Japan's Tatsuma Ito 6-4 6-1 to earn the prestigious clash. Uzbekistan's Denis Istomin beat eighth seed Martin Klizan of Slovakia 6-1 6-2 in another upset.
At the Hopman Cup in Perth, Venus Williams continued her fine form as the United States beat France 2-1 for their second victory in the mixed team event.
Jo-Wilfried Tsonga beat John Isner 6-3 6-2 to put France ahead before Williams fought off Mathilde Johansson 3-6 7-5 6-4 to draw the U.S. level.
The seven-time grand slam champion, elder sister of Serena, then paired with Isner to beat Johansson and Tsonga 6-7 6-2 10-8 in a tight deciding rubber.