Ninth-seeded Matteo Berrettini of Italy has pulled out of the Australian Open before his fourth-round match against Stefanos Tsitsipas because of an abdominal injury.
That allows the fifth-seeded Tsitsipas to move into the quarterfinals at Melbourne Park for the second time in three years. He will face Rafael Nadal next.
Tsitsipas lost to Nadal in the Australian Open semifinals in 2019.
Berrettini said he was told he could hurt himself worse if he tried playing Monday.
He said he was injured in the third set of his fourth-round victory over Karen Khachanov on Saturday.
Berrettini's best Grand Slam showing was reaching the semifinals of the 2019 U.S. Open.