Michael Clarke's career-long back problem has flared up again towards the final days of Australia's tour of England, leaving in doubtful for the deciding one-day international at the Ageas Bowl, while Shaun Marsh has already been ruled out with a hamstring injury.
Clarke's back forced him to miss the Champions Trophy at the beginning of Australia's summer-long stay in England and although he played throughout the Ashes there was often talk that it was causing more worries than were made public
He will be given every chance to prove his fitness for the final ODI, but coach Darren Lehmann has said there is too much at stake in the future for him to be risked if there are any doubts. It also raises the question as to whether Clarke will be part of the one-day tour to India in October, which comes little more than a month before the return Ashes begins.
"It's a big game but if he's not right, we won't risk him," Lehmann told AAP. "It's an important series but we've got another one-day series and an Ashes series coming up."
Clarke scored a superb hundred at Old Trafford to set up Australia's victory - the ground where he also made a century during the Ashes - but did not appear completely at ease in the middle during his 22 in Cardiff on Saturday. He was discomforted by the bounce of Boyd Rankin before falling, slightly unluckily, lbw to Steven Finn.
Australia could, therefore, be fielding a very different top order in a match that Lehmann has termed a "grand final", as they aim to finish a difficult tour with some silverware. Marsh, who has made 0 and 25 in his two innings for the series, picked up a hamstring strain in the fourth match - the latest occasion his career has been interrupted by injury - which is likely to offer a last-ditch opportunity to Phillip Hughes, who has been on the sidelines since he was dropped after the second Test at Lord's.
"We'll look at the pitch but I think that's the probably the way we'd go," Lehmann said. "It gives him an opportunity. He's playing really well and working on his game and that's all we can ask. He's ready to go. Hopefully he gets his chance and away he goes."
Australia were well placed to seal the series with a match to spare when Clint McKay took a hat-trick in Cardiff to leave England 8 for 3, and they later reduced the home side to 144 for 6 but were beaten by Jos Buttler's calculated late assault.
"It gets down to a grand final set-up now, which is great," Lehmann said. "That's what we want the players put under most of the time, although you would have loved to close out the series.
"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."
McKay, who removed Kevin Pietersen, Jonathan Trott and Joe Root to complete a star-studded hat-trick, admitted it was a tough defeat to take after having had England on the ropes. ''The boys are a bit flat,'' he said. ''We had a massive opportunity to take this series home and unfortunately we couldn't deliver. But we'll bounce back and fight hard again on Monday.''