Injured defending champion Maria Sharapova has withdrawn from the Brisbane International.

The five-time grand slam winner announced her withdrawal just hours before she was due to take the court for her opening-round match against Ekaterina Makarova on Pat Rafter Arena.

The 28-year-old said she had a left forearm injury and it was in her best interests to withdraw and ensure she is fit for this month's Australian Open.

Sharapova's withdrawal comes just a day after world No 1 and defending Australian Open champion Serena Williams skipped her opening match of the Hopman Cup in Perth due to knee soreness.


Meanwhile, Novak Djokovic has opened his 2016 season with a 6-2, 6-2 first-round win over German qualifier Dustin Brown at the Qatar Open.

The top-ranked Serb avoided the post-season exhibitions last month after an exhausting 2015 season in which he won three major titles and reached the final in the other.

The Qatar Open was the only tournament in 16 played in 2015 in which Djokovic failed to reach the final, instead losing in the quarter-finals.

Last year, Djokovic won a career-best 11 titles and finished with an 82-6 record.

"Obviously you never know how you're going to start from the blocks," Djokovic said. "I think I used the offseason very well to train to get my body in the right shape, and I think it was a very good start."

Rafael Nadal, seeded No 2 at Qatar, is also looking for a strong start to 2016.

"The most important thing - play better," the Spaniard said, citing the physical and mental struggles he went through in 2015. Nadal managed to recapture some confidence toward the end of the year, posting a 17-5 record following the US Open. The late push enabled him to finish the year ranked No 5, keeping his top five season-ending ranking streak alive for an 11th year.