Rafael Nadal has withdrawn from next week’s Mubadala World Tennis Championship (MWTC) in Abu Dhabi according to Marca.

The Spanish publication is reporting that the world number one is still experiencing some discomfort in his right knee, which forced him to pull out of the remainder of the ATP Finals after playing the first match against David Goffin last month.

Also according to Marca, the 31-year-old had cancelled his training week with Portugal’s Joao Sousa at the Rafa Nadal Academy in Mallorca that was scheduled for December 18-22.

The Spaniard’s withdrawal is yet another blow for the tournament after Milos Raonic and Stan Wawrinka pulled out earlier this week. They have been replaced by Andrey Rublev and Kevin Anderson.

The MWTC is yet to confirm Nadal’s withdrawal and a replacement hasn’t been revealed.