Novak Djokovic fought into the quarter-finals of the Australian Open despite concerns over a muscle injury, seeing off Milos Raonic in four sets.

Djokovic's hopes of defending his title appeared to be in doubt when he said he had a "muscle tear" and was unsure whether he would play the fourth-round clash.

But his history of dominance over Raonic was perhaps a motivating factor in him taking to the court and he stretched his head to head lead to 12-0 with his 300th grand slam win, becoming only the second player in history to reach the landmark.

He did not have it all his own way, a spirited Raonic levelling matters in the second set after losing the first on a tie-break.

However, Djokovic was in control thereafter, progressing 7-6 (7-4) 4-6 6-1 6-4, though a last-eight meeting with Alexander Zverev may prove a sterner test.

There's something special about @DjokerNole #AO2021 | #AusOpen pic.twitter.com/kapWnSRKmm
— #AusOpen (@AustralianOpen) February 14, 2021

Djokovic made it eight wins in nine in tie-breaks with Raonic to take the first set and things looked bleak for the Canadian when he received treatment on his foot in the second set.

But that break proved just the tonic for Raonic as he went on to win a set against Djokovic for the first time in four grand slam meetings.

Yet the tide turned emphatically back in Djokovic's favour in the third – the Serbian winning five straight games to move into a 2-1 lead.

His success came through a familiar strategy against a player of Raonic's power on serve.

Djokovic wasted few opportunities to punish the second serve and consistently took Raonic out of his comfort zone by forcing him into long rallies.

Raonic, to his credit, did save four break points in the fourth set but the dam finally burst and he could not prevent Djokovic from snatching the fifth chance that came his way, the world number one ensuring there was to be no shock as he reached another milestone in a remarkable career.

Get out the record book

The world No.1 becomes the 2nd player in history to notch up Grand Slam match wins #AO2021 | #AusOpen pic.twitter.com/CRcqlnp89N
— #AusOpen (@AustralianOpen) February 14, 2021

Data Slam: Djokovic's delightful dozen

Djokovic is through to a 12th quarter-final in Melbourne, the eight-time winner last failing to reach the stage in 2018, when he lost to Hyeon Chung.

WINNERS/UNFORCED ERRORS
Djokovic – 41/25
Raonic – 50/35

ACES/DOUBLE FAULTS
Djokovic – 10/3
Raonic – 26/3

BREAK POINTS WON
Djokovic – 3/11
Raonic – 1/3