ST KILDA rookie Nick Coughlan has suffered a stress fracture in his right foot and will be out indefinitely.

The defender will wear a moon boot for at least another two weeks.

Coughlan, 20, is yet to make his senior debut. The only time he has represented St Kilda was in a pre-season game against North Melbourne last year, when he picked up eight disposals.

At 193cm, Coughlan has the size to play on a range of opponents. He showed in 12 matches for Sandringham last year, plus another three in the VFL reserves, that he can mark well overhead and reads the play well.

He was drafted at No. 23 in the 2015 rookie draft.

The backman is in the last year of his contract.