Australian middle-order batsman Matt Renshaw has tested positive to COVID-19.

Renshaw has returned to Australia's Test team for the first time since 2018 on the back of a weight of runs at Sheffield Shield level for Queensland.

He has replaced the injured Cameron Green in an Australian side which made three changes, with Ashton Agar and Josh Hazlewood also coming in for Mitchell Starc and Scott Boland.

Renshaw was seen during the national anthem standing slightly away from his teammates, and then away from teammates on the boundary after Australia won the toss and elected to bat first.

Despite humidity, Renshaw was seen wearing a jumper as he watched Australia's top order play out the opening hour of the Test.

It was revealed on Fox Cricket shortly after 11am local time that Renshaw had tested positive to a Rapid Antigen Test for COVID.

With no restrictions currently in Australia around isolation after testing positive for COVID, Renshaw will still be allowed to play out the five days of his Test return as he uses the match to try and force his way into the squad which will travel to India for a four-Test series during February and March.

Under previous restrictions, Renshaw would have been withdrawn from the game.

Renshaw will bat at number six for Australia in the third and final Test against South Africa, with the hosts losing David Warner early in the contest and sitting at 1 for 24 off 11 overs at the time of publication.