Novak Djokovic has withdrawn from next week's Qatar Open to place a further question mark on his participation in the Australian Open.
The Serbian has been sidelined for the last six months and was unable to play in an exhibition match in Abu Dhabi yesterday when an elbow injury flared up.
He said in a statement on his personal website: "Unfortunately, the situation with the elbow has not changed for the better since yesterday. I still feel the pain. Therefore, I will have to withdraw from the ATP tournament in Doha."
Djokovic added: "After thorough consultations with the medical team, we decided to keep up with the therapies and elbow treatments.
"Only when I'm 100% ready to play, will I be able to come back. I hope it will be soon. I want to thank everyone for their patience and understanding."
Djokovic has not played a competitive match since Wimbledon in the summer, and had been due to face Roberto Bautista Agut in Abu Dhabi yesterday before pulling out.
His great rival Andy Murray - who has also been out of action since Wimbledon - stepped in to replace him for the one-set match.