ST KILDA forward Paddy McCartin was concussed for the third time this season in Saturday's loss against Gold Coast.

McCartin was taken off during the first quarter at Metricon Stadium and was ruled out early in the second term after failing his test.

In his post-match press conference, Saints coach Alan Richardson said it was too early to speculate on the severity of the knock.

"It'll be up to the doctors and the medicos, they'll do everything necessary to make sure he's right to play (next week) or not," Richardson said.

"I actually haven't had an opportunity to chat to the docs at this stage.

"Clearly he went off. There's a fair chance our guys are going to be a little bit conservative ... I don't know really." 

The former No.1 draft pick was also concussed against Collingwood in round three and Adelaide in round 11 this season.

He played the week after the Magpies incident but missed one match following the Crows' clash.

Gold Coast is also one player down after wingman Matt Rosa sustained a hamstring injury in the first quarter.

Rosa hobbled off early in the match and will also not return. 

He injured his hamstring in round seven against Melbourne and missed three matches.