All-rounder Cameron Green will miss a substantial part of Australia's Cricket World Cup build-up after being struck on the head by a ball from Kagiso Rabada during the first one-day international against South Africa on Thursday.

An Australia team spokesperson confirmed on Friday that Green will undergo an eight-day concussion protocol during which he will be monitored by the team's medical staff.

He is unlikely to be available until the fifth and final match in Johannesburg on September 17.

It adds to a list of injury concerns for Australia with the World Cup starting in India on October 5, less than a month away.

It also provides an opportunity for Marnus Labuschagne to press his claims for a call-up if a vacancy opens up in the World Cup squad.

Labuschagne was man of the match on Thursday after batting as a concussion substitute for Green. He made 80 not out to steer Australia to an unlikely three–wicket win.

He went out to bat with Australia 72 for five, which then became 113 for seven chasing South Africa’s 222 all out on a tricky pitch.

Injuries meant that only 11 of Australia's World Cup squad of 15 travelled to South Africa. Green's injury reduced that number to ten, which means Labuschagne has a good chance of playing in at least the next three matches, starting with the second game in Bloemfontein on Saturday.

Australian captain Pat Cummins is recovering from a wrist injury. Other World Cup players missing the South African tour because of injuries of varying degrees of seriousness are Glenn Maxwell (ankle), Mitchell Starc (groin) and Steve Smith (wrist).

Australia still have a three-match one-day series in India ahead of the World Cup in which injured players can prove their fitness.

Labuschagne was not due to tour South Africa, having been dropped after a sequence of poor form in one-day games. He was added to the squad when Smith withdrew. After his match-winning performance on Thursday he played down his chances of getting to the World Cup.

"I wasn’t too shocked when I was dropped. But I did say (to the selectors) that I still want to be that person batting for you in the middle order. You’ve just got to sit tight and wait for that opportunity and when the opportunity comes you’ve got to be ready."