Maria Sharapova withdrew from her season-opening event at the Brisbane International rather than risk further damage to a sore left forearm ahead of the Australian Open.
Sharapova, the defending champion, was scheduled to play fellow Russian Ekaterina Makarova on Tuesday but withdrew hours before the first-round match.
The five-time major winner said she'd hurt her forearm in practice a couple of days earlier and pulled out the Brisbane tournament as a precaution ahead of the first Grand Slam tournament of the season, which starts Jan. 18 at Melbourne Park.
Sharapova won the Brisbane and Rome titles in 2015 and lost the final of the Australian Open to Serena Williams, who added the French Open and Wimbledon titles and was two match victories from a season Grand Slam when she lost to Roberta Vinci in the U.S. Open semifinals.
Williams withdrew from her season-opening match at the Hopman Cup in Perth on Monday because of inflammation in her knee, but was hoping to be fit to play for the U.S. team against Australia Gold on Tuesday.
Vinci, meanwhile, moved into the Brisbane International quarterfinals with a 6-1, 6-1 victory over 2014 Australian Open finalist Dominika Cibulkova. She'll meet either top-seeded Simona Halep or 2009 champion Victoria Azarenka in the last eight.
At the ASB Classic in Auckland, New Zealand, former French Open champion Francesca Schiavone lost 7-6 (3), 4-6, 6-3 to Austrian qualifier Tamira Paszek in a first-round match that lasted almost three hours.
Former No.1-ranked players Caroline Wozniacki, Venus Williams and Ana Ivanovic were due on court later Tuesday.