Kei Nishikori announced on Thursday that he will miss the Australian Open in Melbourne having not yet fully rehabilitated the wrist injury that cut his 2017 season short.

In a message posted on his personal smartphone app, Nishikori said he is sorry to miss the year's first major tournament, which he calls his "home" grand slam.

"The Aussie Open is my favorite's the slam that takes incredible care of the players and their teams...and it hurts that I will have to miss it this year."

"My rehab is going well but I am just not ready 100 percent to come back yet in best of five set matches."

The 28-year-old dislocated a tendon in his right wrist while practicing at the Western and Southern Open, a warm-up tournament for the U.S. Open, in Cincinnati in August and did not take the court again in the 2017 season, the first in six that he did not win a title.

Despite several doctors recommending he go under the knife, Nishikori opted to rehab the injury without surgery.

He initially targeted the Brisbane International for his comeback, but in late December he announced he would skip the tournament and the Sydney International, making it little surprise that he is also missing the Australian Open, which starts on Jan. 15.

Nishikori entered the top 10 in the world rankings for the first time in May 2014 and was most recently at his career-high of four in March 2017. Since the injury, he has fallen to 22nd, a rank he was last at in 2013.