MELBOURNE (REUTERS) - Former Australian Open champion Novak Djokovic added an apparent muscle strain in his lower back to concerns about his problem elbow but still overpowered Spaniard Albert Ramos-Vinolas 6-2, 6-3, 6-3 to reach the fourth round of the Australian Open on Saturday (Jan 20).

After holding serve to lead 2-1 in the second set, the 14th seed took a medical time-out and laid down on Margaret Court Arena as a trainer worked feverishly on his lower back.

The injury did little to restrict the six-time winner as the Serb returned to break the 21st seed in the next game before rolling on to a fuss-free victory in two hours and 21 minutes.

Djokovic will face South Korea's young gun Chung Hyeon in an intriguing intergenerational battle for a place in the quarter-finals.