Australia captain Michael Clarke is doubtful for the NatWest Series decider against England at the Ageas Bowl after suffering a recurrence of his chronic back problem.
The tourists already know they will have to make one enforced change and it seems likely they will recall opener Phil Hughes in place of Shaun Marsh - who is ruled out after hurting his hamstring in the fourth match of five in Cardiff.
After England levelled the series at 1-1 there, Clarke is still hoping to play but will be allowed to do so only if he is thought fully fit.
England have stuck to the same line-up throughout the five-match series and any changes would come as a surprise following the three-wicket win at the SWALEC Stadium.
But Australia could be forced to makes some alterations, as coach Darren Lehmann spelled that out as he assessed Australia's selection options.
"It's a big game. But if he's not right, we won't risk him," Lehmann said of Clarke.
"It's an important series, but we've got another one-day series (against India) and an Ashes series coming up."
As for Hughes, who last played for Australia in the second Test at Lord's, the coach added: "We'll look at the pitch, but I think that's the probably the way we'd go.
"It gives him an opportunity. He's playing really well and working on hisgame, and that's all we can ask.
"He's ready to go. We hope he gets his chance and away he goes."
Should Clarke be unavailable, Australia may call all-rounder Glenn Maxwell into their squad for the first time in the series, with room too perhaps for the return of leg-spinner Fawad Ahmed.
Australia have endured a disappointing tour, an early exit in the Champions Trophy followed by a 3-0 Ashes defeat and then a 1-1 draw in two Twenty20s.
Lehmann said: "It gets down to a grand final set-up now - which is great.
"That's what we want the players put under most of the time, although you would have loved to close out the series (in Cardiff).
"We're certainly playing the right brand of cricket. We just made a couple of elementary mistakes.
"Apart from that, we've pretty much played how we want to play. Now the case is we want to finish on a high and get moving on."
Watch the fifth NatWest Series ODI between England and Australia at the Ageas Bowl this Monday from 1.30pm on Sky Sports 2 HD.