Novak Djokovic is through to the fourth round at the Australian Open after beating Grigor Dimitrov in straight sets, but he was made to work for it.

The number four seed was troubled by the hamstring injury carried over from his second-round win against Enzo Couacaud in the first set before winning it on a tie-break.

Djokovic seemed back to normal as he won the second set, but exchanged several breaks of serve with Dimitrov before finally sealing a 7-6 (9-7) 6-3 6-4 win.

The Serbian broke in the first game, but Dimitrov showed admirable grit not to drop serve again, saving set points at 5-3 down before breaking back as Djokovic served for the set.

Despite being visibly hampered by his hamstring, Djokovic saved three set points himself, one of which came in the tense tie-break, before prevailing, the effort it took seeing him briefly collapse to the floor after executing a cross-court volley to seal an opener that lasted 77 minutes.

A medical timeout before second set seemed to make a difference as he continued to trouble the Bulgarian's serve, eventually breaking in the sixth game and going on to take a two-set lead.

Djokovic broke in the first and third games of the third set as Dimitrov began to realise the Serbian's injury issues were not going to be a factor, and although he won a break back, he gave it away to love in the very next game.

The determined 27th seed broke back again before finally holding his serve, but when Djokovic managed to reach his first match point after another long rally, the pair waved to the crowd for noise as they cheered the efforts of both competitors, with Djokovic finishing it off at the first attempt to book a last-16 clash with home hope Alex de Minaur.

Data slam – Unforced errors cost Dimitrov 

There were some impressive rallies throughout the contest, but while the aggressive approach from Dimitrov brought 53 winners, it also led to 50 unforced errors, several of which were on key points.

WINNERS/UNFORCED ERRORS

Dimitrov – 53/50
Djokovic – 28/22

ACES/DOUBLE FAULTS

Dimitrov – 15/4
Djokovic – 11/2

BREAK POINTS WON

Dimitrov – 3/8
Djokovic – 5/12