Muller was able to win more than a handful of games off his own big serve, but Djokovic weathered the storm to continue a remarkable streak of quarter-finals.


The Australian Open favourite won through to his 23rd straight quarter-final appearance in grand slams, a record bettered by only Roger Federer and Jimmy Connors.


His reward is a meeting with Canadian Milos Raonic in the next round, against whom he boasts a 4-0 record.