Australian batsman Travis Head has been ruled out of the fourth Ashes Test and returning a positive test for Covid-19.

Cricket Australia confirmed that the 28-year-old is asymptomatic and will not fly with the squad to Sydney on Friday for the fourth Ashes Test due to start at the SCG on January 5.

The remainder of the Australian squad, their families and the team's support staff have undergone PCR and RAT tests on Friday and are still planning to travel to Sydney on Friday.

A Cricket Australia spokesperson said: “As part of our testing procedures, we are PCR testing players, their families and our support staff daily. Unfortunately, Travis returned a positive Covid-19 result earlier today. Thankfully, he is asymptomatic at this stage. We anticipate that he will be available to play in the fifth men’s Ashes Test in Hobart.

“We are grateful to our exceptional medical staff for all the work they have done throughout this series and we will continue to work with and support the players, their families and staff from both teams.”

Mitchell Marsh, Nic Maddinson and Josh Inglis have joined the Australian squad as additional cover as a precautionary measure, although Usman Khawaja appears most likely to replace Head in the XI.

On Friday, there was a huge jump in confirmed Covid-19 cases in Sydney, were the fourth Test will be played, with 21,151 infections diagnosed up from 12,226 on Thursday.

The Boxing Day Test earlier this week was jeopardized after positive cases within the England camp, while Third Test match referee David Boon tested positive on Thursday.

Australia captain Pat Cummins missed the second Test in Adelaide after being a close contact of a confirmed Covid-19 case.

Head becomes the first player to miss a Test in the Ashes series due to testing positive as Covid-19 closes in on the series.