World number one Rafael Nadal has withdrawn from next week's ATP tournament in Buenos Aires because of a lingering back injury, the Spaniard announced on Thursday.
Nadal posted a video on his official YouTube page, in which he said he had failed to fully recover from the back problem that plagued him during last month's Australian Open final.
"I wanted to make an announcement that really fills me with sadness. I will not be able to play in the tournament in Buenos Aires," Nadal said.
"Since I came back from the Australian Open with my back injury I have not been able to train.
"It is impossible for me to prepare properly for a tournament as important as Buenos Aires, so very unfortunately I have to take this decision."
The 13-time Grand Slam champion was beaten 6-3, 6-2, 3-6, 6-3 by Switzerland's Stanislas Wawrinka in the final in Melbourne.