Novak Djokovic is facing a race to be fit for his last-16 match against Milos Raonic on a day of intriguing match-ups at the Australian Open today.
Gland Slam winners Garbine Muguruza, Naomi Osaka, Serena Williams, Dominic Thiem, Iga Swiatek and Simona Halep are also in behind-closed-doors action.
Djokovic suffered an abdominal injury during his third-round win over Taylor Fritz and did not practise on Saturday.
“I don’t know if I will step on court,” the Serb said after Friday’s victory.
The world number one has been given the maximum time to recover as his match against Raonic is the final one on Rod Laver Arena on Sunday.
Eight-time Australian Open champion Djokovic needed courtside treatment against Fritz and later said he thought he had torn a muscle, adding: “I don’t know if I will recover from that in two days.”
The top seed has a perfect record of 11 wins from 11 matches against 30-year-old Canadian Raonic, including three-set victories in the Australian Open quarter-finals in 2020 and 2015.
Five Grand Slam winners play on the same court in the women’s singles fourth round on a brilliant-looking schedule on Rod Laver Arena.
It begins at 00:00 GMT with Spain’s Muguruza, a winner at the French Open and Wimbledon, facing Japan’s Osaka, who has won the US Open twice and triumphed in the Australian Open in 2019.
“I don’t think we’ve played each other before,” said Muguruza, who has not dropped a set so far. “I am just happy with being in the second week of a Grand Slam. It shows my game is there.”
Williams, 39, is one Slam away from matching Margaret Court’s all-time record of 24 major singles titles and is second on Rod Laver Arena. She takes on 22-year-old Belarusian Aryna Sabalenka, with the seventh seed aiming to reach her first Grand Slam quarter-final.
All matches will be played without any fans in attendance until at least Thursday because of a snap five-day lockdown for the state of Victoria.