MELBOURNE (Australia): Diego Schwartzman is well aware that beating Novak Djokovic will be a tall order after he advanced into the Australian Open fourth round.
Schwartzman heads into his fourth meeting with the 16-times Grand Slam winner on Sunday having never defeated the Serb.
Djokovic is in ominous form in his thumping 6-3 6-2 6-2 win over Nishioka to stay on course for an eighth title in Melbourne.
In other Sunday match ups, Swiss world number three Roger Federer, who came back from the brink to edge past Australian battler John Millman in five sets, will hope his fourth-round meeting with Marton Fucsovics of Hungary will be physically less demanding.
Double Wimbledon champion Petra Kvitova has scythed down opponents without dropping a set in the tournament so far and the seventh seed will look to produce yet another ruthless display against Maria Sakkari of Greece.
Top seed Ash Barty will resume her quest to become the first homegrown champion at the tournament since 1978 when she meets 18th-seeded American Alison Riske while Tunisian sensation Ons Jabeur takes on Wang Qiang who knocked out Serena Williams.
Canada’s Milos Raonic meets Marin Cilic of Croatia in a battle of the big servers before unseeded American Tennys Sandgren faces 12th seed Fabio Fognini of Italy.
Teenager Coco Gauff, who dumped defending champion Naomi Osaka in the last round and felled Venus Williams in her opener, squares off against fellow American Sofia Kenin for a spot in the quarter-finals.
