New Zealand captain Kane Williamson was among three players ruled out of the third Test against Australia on Friday, as the illness-hit Black Caps made five changes to their XI.

Already missing Trent Boult due to his fractured hand, New Zealand were dealt further blows as Williamson, Henry Nicholls and Mitchell Santner all fell victim to a virus that has swept their camp.

Tom Latham captained the tourists in Williamson's absence, while Glenn Phillips was handed a Test debut having only arrived in Sydney as cover the previous evening.

The Black Caps' other changes saw Jeet Raval, Will Somerville, Todd Astle and Matt Henry included, with Tim Southee the fifth player to drop out of the line-up from the last Test.

"It's been a tough 48 hours for us," said Latham at the toss. "We've had a bit of sickness and a virus that has gone through the team, which is unfortunate.

"Obviously Kane and Henry are down and Mitch Santner is down, those guys gave their best chance this morning to be right but unfortunately they're not right."

The loss of Williamson represented a particularly tough break for New Zealand, with the 29-year-old averaging 51 in Tests and having made 21 centuries from 78 appearances.

Australia, who won the toss and opted to bat, were unchanged, with Nathan Lyon continuing as the sole frontline spinner despite the call-up of the uncapped Mitchell Swepson.

The hosts are seeking a 3-0 series sweep after comfortably winning the first two Tests in Perth and Melbourne.