The top-ranked women's player had a bye in the first round, but withdrew from her second-round match, which would have pitted her against Marion Bartoli.
Williams, 31, is off to a 12-2 singles start in 2013. She won the WTA Brisbane International in early January, but then fell in the quarterfinals of the Australian Open nearly a month ago. Williams returned to action in Qatar last week, claiming the WTA No. 1 ranking, but lost to Victoria Azarenka in the tournament final.
According to the AP report, Azarenka also withdrew from Dubai because of an injured right foot.
Williams remains the top female player in the world at the moment, but is not far ahead of Azarenka. Despite her ranking, though, Williams' slow start has caught the tennis world by surprise, especially following her dominant stretch to finish out the 2012 season.
She won Wimbledon for the fifth time in her career last summer before winning Olympic gold in London. Williams capped off the Grand Slam season with her fourth career U.S. Open title in September.
The 15-time Grand Slam champion will now look to rest up in preparation for the long, grueling tennis season ahead.
It remains to be seen how long Williams is sidelined by the injury, but the next big tournament on the schedule is the BNP Paribas Open at Indian Wells, which begins in March.
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