Six-time champion Novak Djokovic overcame an injury concern to beat Albert Ramos-Vinolas and reach the Australian Open fourth round.

Djokovic received medical treatment in the second set for a lower back or leg injury but came through 6-2 6-3 6-3.

He is playing in his first event since Wimbledon in July last year after a six-month lay-off with an elbow injury.

Despite the convincing scoreline Djokovic was not at his best and was often frustrated on court.

However he closed out the match in two hours, 23 minutes and progresses to face 21-year-old South Korean Hyeon Chung who is making his first appearance in the last-16 of a Grand Slam.

"It was a straight-set win but almost two-and a-half-hours. It was not that easy and comfortable," the 12-time Grand Slam champion said.

Despite early opportunities on the Djokovic serve for Ramos-Vinolas, the Spaniard was the first to be broken, in the fourth game, as the Serb took the first set.

At points it looked like a regulation match for Djokovic but concerns for his chances were raised when he called for the trainer with the score 2-1 in the second set.

He continued to hobble and stretch his left leg following the treatment but fought off four break points for Vinolas-Ramos at 4-2 in the second set to maintain his advantage, after which the match always looked to be going in Djokovic's favour.