Venus Williams has pulled out of the Qatar Open due to a persistent lower back injury.
The world number 23's Australian Open campaign was blighted by the complaint, which also forced her to withdraw from last week's Paris Open.
Andrea Hlavackova of the Czech Republic will take Williams's place in the competition, in which her sister Serena is due to compete.
Williams has also pulled out of the United States' Fed Cup match against Italy scheduled for February 9 and 10.
