Last updated on .From the section Tennis

Djokovic received lengthy medical attention early in the second set

2018 Australian Open Dates: 15-28 January Venue: Melbourne Park Coverage: Watch highlights on BBC Two, the BBC Sport website and app. Live commentary on the best matches on BBC Radio 5 live, sports extra and online.

Roger Federer and Novak Djokovic both reached round four of the Australian Open with straight-set wins - although the Serb suffered an injury scare.

Switzerland's five-time champion Federer beat Richard Gasquet 6-2 7-5 6-4 to progress to the last 16.

Six-time winner Djokovic had treatment on his lower back and leg but saw off Albert Ramos-Vinolas 6-2 6-3 6-3.

"It's nothing major to be concerned about. It's things that surface every day. I guess it's normal," he said.

Djokovic, 30, is playing in his first event since Wimbledon last year after a six-month lay-off with an elbow injury.

Despite the convincing scoreline he was not at his best on Margaret Court Arena 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.

There were early opportunities on the Djokovic serve for Ramos-Vinolas, but 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.

"These kind of circumstances in which I'm in at the moment are quite different," added Djokovic.

"I've never faced a situation where I didn't compete six months.

"That's why I'm kind of forced to be very cautious of what happens day-to-day, be dedicated to my body and training."

Gasquet fails to halt losing streak

Federer, 36, comfortably extended his record over Gasquet to 17-2, with the Frenchman only ever having beaten the 19-time Grand Slam champion on clay.

Gasquet, 31, was behind almost immediately in Saturday's night session and failed to muster a single break point until late in the third set, when he clawed his way back to 4-4.

Federer slammed the door shut on any sustained comeback, however, clinching victory with a brilliant return game after one hour and 59 minutes with two backhand winners.

"I was able to maybe stay a little more on the offensive than he was," said the Swiss.

"The second set was tight, the match was close and the end could have gone to a tie-break."

The defending champion will face Hungarian world number 80 Marton Fucsovics in the last 16.