One of the season's traditional curtain-raisers, the Qatar Open, begins tomorrow. However, with the late withdrawal of Novak Djokovic, the tournament is shorn of its usual A-list headline acts. Djokovic, the champion in Doha for the past two years, pulled out on Saturday because of continuing problems with a niggling elbow injury. His absence has also placed doubtsover his participation in January's Australian Open. This year, though, the field in Qatar is less eye-catching but may provide an opportunity for the new stars of tennis to push through. With Djokovic gone, the number one seeding has been handed to world number five, Dominic Thiem.