Melbourne VIC, Australia, 15 December 2016 | AAP

Ajla Tomljanovic has been ruled out for the entire summer in another demoralising setback for the fallen Australian tennis star.

The one-time world No.47 had been due to make her long-awaited comeback from a shoulder injury at next month’s Kooyong Classic in Melbourne.

Alas, Tomljanovic has had to withdraw, extending the 23-year-old’s layoff to 12 months.

The Croatian-born talent only played two matches in 2016, her last outing coming at the Australian Open last January before she underwent surgery.

Tomljanovic’s ranking has plummeted to No.929, but she had been rehabbing and training in Florida and Australia, often with boyfriend Nick Kyrgios, in the hope of finally returning to the tour.

“I am disappointed to not be able to participate in the upcoming Kooyong Classic. I’ve been doing everything I can to prepare for it,” Tomljanovic said.

“But I just need more time to be fully ready to play after being away from the tour for a while.

“I look forward to playing next year in front of the wonderful Australian fans.”

Kooyong Classic tournament director Peter Johnston said he felt for Tomljanovic.

“She has been working so hard to get herself ready for Kooyong and Australia. It is frustrating for her and we wish her well,” he said.

“We are in the process of finalising her replacement in our women’s field.”