EMERGING Carlton defender Caleb Marchbank is set to miss the next month after scans revealed a hairline fracture in his right shoulder.

The 20-year-old has become a key cog in the Blues' underrated backline in his first season since switching from Greater Western Sydney, and was the round six NAB AFL Rising Star nominee.

Marchbank sustained the injury when he landed heavily on his right shoulder after a marking contest early in the final quarter of last week's 12-point defeat to Adelaide.

"Recent scans have revealed a hairline fracture of his scapula, meaning Caleb is expected to miss the next three-to-four weeks of football," Carlton head of football Andrew McKay said.

"The good news is it is stable, so he won't require surgery. While it is disappointing for both us and Caleb, we are confident we will welcome him back to the field well and truly before the end of the season."

Marchbank had played all 14 games for the Blues and proven an intercept specialist, but the shoulder setback continues a torrid run for the 2014 No.6 pick.

His previous injuries include back stress fractures, a torn meniscus in his right knee, an ankle syndesmosis issue and a dislocated right shoulder.