Jack Dempsey ruled out of Australia's northern hemisphere tour

Jack Dempsey will miss Australia's autumn tests against England, Wales and Scotland due to a "serious" injury.

The flanker had to be assisted off the field due to an apparent hamstring injury in Australia's 31-28 win over the Barbarians on Saturday, which proved a costly affair for Michael Cheika side.

Lukhan Tui also suffered a hamstring strain against the Alan Jones-coached Barbarians and fellow lock Rory Arnold is likely to be left off the tour after being forced out of the game with a knee injury.

"Whatever it is, it's serious," Wallabies coach Cheika told local media when discussing Dempsey's injury.

"There's no doubt he'll be out of the tour. He's in a fair bit of pain. It's unfortunate his season is over."

Dempsey's injury is a huge blow for the Wallabies and the 23-year-old, who was Man of the Match in the upset of the All Blacks in Brisbane last week.

An imposing presence at the breakdown and composed with ball in hand, Dempsey made his test debut against Italy in June but made the blindside flanker position his own with a string of fine performances in the latter half of the Rugby Championship.

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All-but-forgotten loose forward Ben McCalman has put himself in contention for Cheika, though, with an impressive turn off the bench on his comeback from a horror run of shoulder injuries.

"Ben McCalman put his hand up pretty strongly for a guy who hasn't played a lot of footy," Cheika said of the 49-test number eight, in Wallabies colours for the first time since August last year.