Two-time Grand Slam champion Victoria Azarenka pulled out of her Qatar Open semi-final match in Doha due to a back injury, organisers of the WTA 500 event said on Friday.

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

Muguruza will meet the winner of the Friday's second semi-final between Czech Petra Kvitova and American Jessica Pegula.

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