Novak Djokovic sought a medical timeout for a lower back injury as he claimed his 11th round of 16 appearance at the Australian Open on Saturday.

The six-time champion advanced with a clear-cut 6-2, 6-3, 6-3 win over Spanish 21st seed Albert Ramos-Vinolas in 2hr 21min on Margaret Court Arena.

But there was concern in his camp when the former world No.1 sought a medical timeout early in the second set for treatment to his lower back. Djokovic later played down the extent of the problem, saying “it’s okay, nothing major”.

The Serb, looking for matches after a six-month lay-off with right elbow trouble, will face South Korea’s Chung Hyeon in Sunday’s fourth round after he shocked fourth seed Alexander Zverev.

The injury was a fresh worry for the 12-time Grand Slam champion, whose ranking has slipped to 14 after an inactive second half of 2017.

Djokovic, who was upset by Denis Istomin in the second round of last year’s tournament, was workmanlike as he broke the Spaniard’s serve five times, although his errors outnumbered his winners 40-37. It took his record against Ramos-Vinolas to 5-0 with two of the wins at Slams.

Should Djokovic beat Chung he is facing a potential quarter-final against Austria’s fifth seed Dominic Thiem, who must first get past American surprise packet Tennys Sandgren on Monday.