A lack of consistency has cost Marnus Labuschagne a place in Australia's ODI squad, but the Test star's dream of playing in a World Cup was not yet over according to selection chair George Bailey.

Speaking after Cricket Australia revealed the squads for white-ball tours of South Africa and India, Bailey also confirmed that Steve Smith was set to open the batting in upcoming T20Is against the Proteas before a busy one-day schedule to follow.

Labuschagne was the most notable absentee of an extended 18-player World Cup squad announced today, with selectors set confirm an ICC-mandated 15-player group for the showpiece event by late September.

After a bright start to his ODI career in 2020, in which he scored 40 or above in six of his first eight innings, Labuschagne's returns at 50-over level have gradually diminished.

Since New Zealand's tour of Far North Queensland to kick off the 2022-23 summer, the right-hander has managed 170 runs in eight innings at an average of 24.29.

Asked whether the decision to drop Labuschagne was part of a longer-term strategy or due to recent results, Bailey said the world's No.5 ranked Test batter had not delivered steadily enough at one-day level.

"It is form-based. We know Marnus at his best is good enough to hold down a spot in the one-day team, we just haven't seen enough of it consistently in the role that we'd like him to do," Bailey told reporters.

"Leading into the World Cup there's some opportunities for some others to get a bit more game time in there.

"We've been really clear with Marnus; he's going to be part of some Australia A games at the same time so he can focus on some white-ball cricket."

Labuschagne's last resort to push his way back into the conversation would appear to be by featuring in the upcoming 50-over matches for Australia A against New Zealand A.

An Australia A squad to be coached by Adam Voges, due to be released later this week, will play three 50-over games against New Zealand A between September 10-15.

Queensland's Marsh One-Day Cup campaign begins with a clash with Western Australia on September 24, with a second match against South Australia four days later.

Bailey said the selectors can push back confirming a 15-player World Cup squad until September 28, which meant Labuschagne's plight to play in his first ever World Cup was not over, albeit he would need to come from behind to secure a spot on the plane to India.

"Clearly the squad that we've got going to South Africa have the front-running for that.

"But Marnus, the age that he is and the skillset he has, we've got no doubt that he'll play a part in one-day cricket in the future. 

"I couldn't give you a time on when that will be, but certainly we know at his best he can play a really important role."

Australia's selection chair confirmed that after a scintillating KFC BBL|12 campaign in which he scored back-to-back centuries opening the batting for the Sydney Sixers, Steve Smith would be elevated to opener in the three-match T20 series against South Africa.

"He'll open in South Africa and I guess he's the one guy out of those multi-format players who is heading across that we wanted to give that opportunity," Bailey said of Smith, who has never opened at T20I level.

"It was pretty exhilarating, his innings in the Big Bash, and highlighted his skillset and what he can do.

"The way he played in the Big Bash, that's something we want to see replicated internationally, so it's important that he gets an opportunity to have a crack at that.

"He was really keen to come across and be a part of that, and that may mean that he has a rest in a couple of the one-dayers … to make sure he's fresh and can impact the one-day game as much as we want through the World Cup, he's such an important player for us there as well.

"But certainly excited to see him bring that Big Bash opening outlook into that role internationally."

Asked about Australia's opening ODI combination – last occupied successfully by Travis Head and Mitchell Marsh during Australia's 2-1 win over India in March – Bailey reiterated the importance of flexibility and flagged either David Warner or Marsh "rolling through the middle" in matches to come.

He also confirmed that one of Smith, Marsh, Josh Hazlewood or Alex Carey would take on the ODI captaincy duties for Pat Cummins in South Africa while he recovers from a fractured wrist.

Australia's run to the ODI World Cup

2023 Qantas Tour of South Africa

September 7: First ODI, Bloemfontein (D/N), 9pm AEST

September 9: Second ODI, Bloemfontein (D/N), 9pm AEST

September 12: Third ODI, Potchefstroom (D/N), 9pm AEST

September 15: Fourth ODI, Centurion (D/N), 9pm AEST

September 17: Fifth ODI, Johannesburg, 6pm AEST

2023 Qantas Tour of India

September 22: First ODI, Mohali (D/N), 6pm AEST

September 24: Second ODI, Indore (D/N), 6pm AEST

September 27: Third ODI, Rajkot (D/N), 6pm AEST

Australia's 2023 ODI World Cup fixtures

October 8: v India, Chennai (D/N), 7.30pm AEDT

October 13: v South Africa, Lucknow (D/N), 7.30pm AEDT

October 16: v Sri Lanka, Lucknow (D/N), 7.30pm AEDT

October 20: v Pakistan, Bengaluru (D/N), 7.30pm AEDT

October 25: v Netherlands, Delhi (D/N), 7.30pm AEDT

October 28: v New Zealand, Dharamsala, 4pm AEDT

November 4: v England, Ahmedabad (D/N), 7.30pm AEDT

November 7: v Afghanistan, Mumbai (D/N), 7.30pm AEDT

November 12: v Bangladesh, Pune, 4pm AEDT

Australia ODI squad: Pat Cummins (c), Sean Abbott, Ashton Agar, Alex Carey, Nathan Ellis, Cameron Green, Aaron Hardie, Josh Hazlewood, Travis Head, Josh Inglis, Mitchell Marsh, Glenn Maxwell, Tanveer Sangha, Steve Smith, Mitchell Starc, Marcus Stoinis, David Warner, Adam Zampa
* To be trimmed to 15 for the ODI World Cup