ST KILDA defender Dylan Roberton has been withdrawn from St Kilda's side that will travel to Geelong on Saturday night after failing to overcome the effects of concussion.

Roberton was left dazed after receiving a heavy bump from Port Adelaide backman Tom Jonas at Etihad Stadium last Saturday night – a bump that earned Jonas a three-match suspension.

The dashing Roberton had been named at centre half-back against the Cats but has failed subsequent medical tests.

He has been replaced by big man Rhys Stanley.

Roberton's concussion was a talking point after the clash with Port Adelaide.

The 22-year-old former Docker received the knock late in the second quarter and was initially cleared to play on by club medical staff. 

However, his true condition was revealed during a brief half-time interview with Channel Seven's Cameron Ling, after which he was checked by club staff before being substituted out of the match.