Bianca Andreescu will not return from her troublesome knee injury in time to defend her Indian Wells title next week.
The Canadian claimed the first championship of her WTA Tour career in California last year, kickstarting an outstanding 2019 season.
Andreescu claimed the Rogers Cup and then triumphed at the US Open, before a knee problem at the WTA Finals dealt her the latest setback of an injury-plagued career.
The world number four has not played since and will not be able to make her season debut at the upcoming WTA Premier tournament either, she revealed on Saturday.
"As many of you know, I've been working through an injury I suffered last year during the WTA Finals," Andreescu said.
"It's been a long road to recovery and, while I was looking forward to getting back on court and defending my title at Indian Wells, unfortunately I'm still not 100 per cent.
"I would like to thank you all for your continued support and [for] sticking with me on this journey. Your kind words have been so uplifting.
"While I am disappointed that I am not competing next week in a tournament where I have such great memories, I am focused on my recovery and rehab and working hard to get back on the court as soon as possible."