Victoria Azarenka withdrew from the Doha Open Friday ahead of her semi-final clash with Garbine Muguruza, blaming injury which was on display as she battled through her last-eight tie against Elina Svitolina. "Azarenka is withdrawing from her semi-final match tonight due to a back injury. Muguruza wins by walkover," the WTA said in a statement. Azarenka, a two-time winner of the Australian Open in 2012 and 2013, reached the quarters by seeing off Ukrainian top seed Svitolina, 6-2, 6-4. But back pain dogged her effort and saw her visibly slow down during the second set. "The pain didn't really get any better. I'm pretty proud of the way I handled it mentally. I tried to approach it and focus on the things that I could do rather than the things that I couldn't do," she said after the match. Muguruza will face either Petra Kvitova or Jessica Pegula in the final Saturday depending on the outcome of their semi-final clash. gw/td