1. Will Halep recover to face 'strong' Osaka?
Simona Halep's powers of recovery will be put to the test on day eight of the Australian Open on Monday when the world number one meets Japan's Naomi Osaka in a tricky fourth round clash.
Two days after spending three hours and 45 minutes to get past American Lauren Davis in the third round, the top seed will be out on Margaret Court Arena attempting to reach the quarter-finals for the third time.
Halep was already carrying an ankle injury from her second round match and the 20-year-old Osaka, who took her to three sets in both their previous meetings, possesses just the sort of power game that can cause her problems. Factbox
"The ankle's sore, it's not recovered," Halep said after the Davis marathon.
"Osaka is hitting strong, so strong. I have to be strong, if I can, on my legs, and just stay there, playing fast, opening the court, as I do all the time."
2. Djokovic also faces stern test
Novak Djokovic also faces a stern test, of a nascent comeback in his case, when he takes on South Korea's Chung Hyeon looking to edge a step closer to a mouth-watering semi-final against Roger Federer.
The bespectacled 21-year-old Chung, who won the inaugural Next Gen ATP Finals in November, lost in three sets to the Serbian at Melbourne Park in 2016.
Djokovic, who received treatment on his lower back in his third round match and is still playing with a sleeve over the troublesome elbow that sidelined him for half a year, said he was expecting a tougher tie this time.
3. Hsieh Su-wei trains her giant-killer's gaze Kerber
In other action, Taiwan's Hsieh Su-wei, who has beaten world number three Garbine Muguruza and former world number two Agnieszka Radwanska in the last two rounds, trains her giant-killer's gaze on in-form 2016 champion Angelique Kerber.
Madison Keys takes on eighth seed Caroline Garcia in the first match of the day on Rod Laver Arena, while Barbora Strycova and Karolina Pliskova, who fell out over a coach last year, meet in an all-Czech grudge match to close the day.
4. Federer meets Fucsovics
Defending champion Federer, himself looking to match Djokovic's tally of six Melbourne Park titles, will attempt to do his part to set up the blockbuster clash when he meets Hungary's Marton Fucsovics for a place in the last eight.