However the Swiss, who would be chasing a record 17th grand slam title in Australia, was confident he would be fit for the tournament in Melbourne, which starts on Jan. 16.
“I hurt my back in the second round match (on Wednesday),” Federer said in a news conference.
“I don’t think it’s the right time to risk anything right now. For Australia, I’m optimistic. It’s not good, but it isn’t crazy bad.
“Without playing and the right treatment I will get through it in the next few days. I have a long journey in front of me, but hopefully mid next week I should be 100 percent again.”
Federer started the Qatar tournament in imperious form, dropping just nine games in his opening two matches, but he struggled in Thursday’s quarter-final against Andreas Seppi 6-3 5-7 6-4.
Federer had been due to play Frenchman Jo-Wilfried Tsonga in the semi-finals on Friday. Tsonga will now meet either top seed Rafael Nadal or Gael Monfils in the final.
(For more sports news and updates, follow Ahram Online Sports on Twitter: @AO_Sports).