Former world No.1 Roger Federer said on Friday he was excited to return to competitive tennis at next week's Qatar Open after a year-long absence. 

The 20-time Grand Slam champion has not played a tournament since his Australian Open semi-final exit against Novak Djokovic last year, undergoing two knee surgeries since. 

"Here we are, about to take off to fly to Doha. It's been a year since my last event," Federer, 39, said in a video posted on his Twitter feed.

The tennis great's long absence on court has caused suspicion of his retirement from the sport.

"I can tell I'm very excited... it's been a long and hard road. I know I'm not at the finish line yet but it's good, I feel I'm in a good place, I've been practicing very well and I just feel really pumped up." The Qatar Open starts on Monday. 

Meanwhile, on the women's side, two-time Grand Slam champion Victoria Azarenka pulled out of the WTA 500 Qatar Open semi-final match in Doha due to a back problem she sustained in her quarter-final meeting with Elina Svitolina. 

The eighth-seeded Belarusian was scheduled to face Garbine Muguruza, who received a walkover into Saturday's final. 

Muguruza will meet Czech Petra Kvitova, who beat qualifier Jessica Pegula 6-4 6-4 to storm into her third Doha title clash in the last four years. 

Azarenka's injury casts doubt on her participation in next week's Dubai Tennis Championships. 

(With input from Reuters)