Langer mulls changes in ODI tri-series

Justin Langer is losing sleep as he mulls Australia's XI for their next ODI tri-series clash, saying selection is the hardest aspect of coaching.

Stand-in coach Langer and on-duty selector Trevor Hohns have a couple of tough calls to make ahead Australia's third match of the series against South Africa in St Kitts on Saturday (Sunday 3am AEST).

The most difficult appears to be whether Adam Zampa or Nathan Lyon is dropped.

Zampa and Lyon could yet stay in the side, having both impressed on a spin-friendly pitch in Georgetown.

But Warner Park is a smaller venue, while its wicket is likely to offer the tweakers a lot less assistance.

Fit-again spearhead Mitchell Starc is set to return after being rested from the last-start 47-run loss to the Proteas which followed an opening win over the Windies.

The top six is far from settled, with Glenn Maxwell and Mitch Marsh both having started the series poorly with the bat.

James Faulkner and George Bailey are both waiting in the wings, as is would-be debutant Travis Head.

"You've got to give them every opportunity but you also got to pick the best XI," Langer said of Maxwell and Marsh.

"Performance is one thing you look at, different conditions ... we have to be fair and consistent.

"Selection is the hardest part of coaching.

"You lose sleep at night about it because there's five guys (in the 16-man squad) who have to miss out ... there's so much depth."

Langer suggested the current problem with Maxwell, Marsh - and indeed most of their teammates who folded for a total of just 142 against the Proteas in Guyana - was adapting to local conditions.

"It's been the theme," Langer said.

"They're all very good players but they have to learn how to adapt.

"We all do. Davey Warner showed it in the first game, Aaron Finch and Nathan Lyon in the second.

"The great players adapt to different environments, different conditions, different opposition and different formats."

Langer, coaching the side while Darren Lehmann takes a temporary break, gave little away about the various selection conundrums.

But the former Test opener made it clear he wouldn't shy away from making tough calls.

"That's what you get put into a position of responsibility for ... that's what we're here to do," Langer said.