World number one Novak Djokovic claimed grand slam win number 300, prevailing in four sets against Milos Raonic despite injury concerns.
Novak Djokovic will not train on Saturday as planned, the injured champion leaving his Australian Open fate in the hands of doctors.
Novak Djokovic and Dominic Thiem are both through to the last 16, but the Austrian looked to be in better shape after his triumph.
He found a way to prevail against Taylor Fritz, but Novak Djokovic does not know if he will be fit to face Milos Raonic.
Novak Djokovic said he had "no respect" for Nick Kyrgios and refused to reply to the Australian's response after winning at Melbourne Park.
Pablo Carreno Busta's hopes of beating Diego Schwartzman to the last ATP Finals qualifying spot were ended by Rafael Nadal in Paris.
Gilles Simon sprung a surprise on Denis Shapovalov in Cologne, where Diego Schwartzman made serene progress to round three.
Top seed Alexander Zverev has won 11 of his last 12 hard-court matches, but it was not all plain sailing against John Millman on Wednesday.
Andrey Rublev and Denis Shapovalov will fight it out for a place in the final of the St. Petersburg Open on Saturday.
Andy Murray entered the ATP 250 tournament in Cologne to build up match practice, but he tumbled out in the first round on Tuesday.