The world number two, and recently-crowned ATP World Tour Finals champion, beat 44th-ranked veteran Stepanek 7-5, 6-1, 6-4 in two hours and 10 minutes.u00a0"The 1-0 lead is very important for us," the 26-year-old Djokovic told a frantic crowd in the sold-out Belgrade Arena sitting 15,500 people.

Novak Djokovic