Marsh has endured a difficult season and lost his Test place to Beau Webster for the final match against India at the SCG, having made 73 runs in seven innings and performing a limited role with the ball during the Border-Gavaskar Trophy. His fitness was a regular topic of conversation during that five-Test series.

He played a lone BBL game on January 7 after the Test series against India but then rested from the last three matches of the BBL season to mentally and physically refresh ahead of Champions Trophy. But his back remained a serious issue and the selectors have ruled him out of the tournament. A CA statement described the issue as "lower back pain and dysfunction" but did not reveal specifics.

"Mitchell Marsh has been ruled out of the upcoming ICC Men's Champion's Trophy with ongoing lower back pain and dysfunction," the statement said. "The National Selection Panel and Australian men's medical team ruled Marsh out of the tournament with the injury which has not responded sufficiently to rehabilitation.

"His lower back pain flared in recent weeks leading the NSP to make the longer term decision for Marsh to complete a more extended period of rehabilitation. Marsh will now undergo a period of further rest and rehabilitation as part of his return to play plan. The NSP will meet to decide on a replacement for Marsh in due course."

Australia have a lot of batting cover in the squad already, including spare wicketkeeper Alex Carey, and could choose another allrounder to replace Marsh. Will Sutherland played ODI cricket last year and would have been on the tour of the UK in September had he not suffered a back injury. Webster has not played ODI cricket but could be called upon if needed, while Cooper Connolly is also a spin-bowling allrounder although Australia have four batters who can bowl spin in the squad already. Cameron Green remains unavailable as he continues his rehab from back surgery in October.

Cummins also remains a doubt for the tournament due to an ankle injury he carried through the Test series against India, so with Marsh out of contention Australia may need another captain which would bring Steven Smith, currently in charge of the Test team in Sri Lanka, Travis Head and Josh Inglis into contention. Head has captained the T20I but has not led the ODI side. Inglis captained both in the recent home summer as Australia have half an eye on their future leadership options despite Cummins looking set to push through to the 2027 ODI World Cup.

Marsh was a key part of Australia's 2023 ODI World Cup triumph where he scored centuries against Pakistan and Bangladesh. Since being used consistently in the top order from March 2023 he has averaged 44.54 in ODIs with a strike-rate of 109.13.

A year ago, Marsh was named the Allan Border Medalist following his successful comeback to Test cricket alongside his consistent limited-overs returns.

Champions Trophy squads can be freely amended until February 11 after which approval is required from the technical committee.

Australia play two ODIs in Sri Lanka on February 12 and 14 in preparation for the tournament.

Legspinner Tanveer Sangha will fly to Galle to join Australia's Test and ODI squads as a development player, but is not in contention for selection. Left-arm quick Spencer Johnson is doing the same for the ODIs, with the pair also a chance to travel to Pakistan for the Champions Trophy.