North Melbourne rookie Oscar Junker will be sidelined for up to four months after breaking his tibia.

Junker suffered the injury during North's practice match against Werribee last Saturday after landing awkwardly.

It was initially thought the 19-year-old had injured his ankle, but scans revealed the leg fracture.

Junker had been enjoying a solid first pre-season at Arden Street, but is now not expected to return to the field until round seven or eight.

The 193cm midfielder co-captained the Western Jets in last year's TAC Cup and joined North via pick No.28 in last year's NAB AFL Rookie Draft.

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