Rafa Nadal is aiming to return from injury at an exhibition event in Abu Dhabi next month before playing another tournament in his buildup to the Australian Open, the world number five said. Nadal struggled with back issues at the start of this year and pulled out of Wimbledon and the Tokyo Olympics. He last competed in August at the Citi Open in Washington. He announced ahead of the U.S. Open that the injury to his left foot would rule him out for the rest of the year but said on Monday he might return at the Dec. 16-18 Mubadala World Tennis Championship exhibition event. “My plan is to play …