Carlton will have to beat St Kilda without Charlie Curnow to seal an AFL finals spot after the key forward failed to overcome an ankle injury. 

Curnow had been named on Thursday to return for Sunday's match at Docklands but was officially ruled out on Friday.

It is a blow to the Blues' hopes of locking in a top-eight berth, while Mitch McGovern (hamstring) also appears unlikely to prove his fitness to face the Saints.

The eighth-placed Blues can book a spot in the finals with a win over the Saints, but a loss will give Fremantle a chance to leapfrog them on the ladder.

"We sort of thought that he [Curnow] might be able to pull up pretty well from some of the things that he did the other day, but hasn't pulled up as well as what we expected," Blues coach Michael Voss said.

"So we'll just make that call now and obviously it gives us an opportunity to be able to lock in on what our forward mix is going to be."

McGovern did not train with the main group on Friday and clearly appears in some doubt to play.

"We'll give him every opportunity to be able to get up," Voss said.

Harry McKay (quad), Jack Martin (hamstring), Adam Saad (hamstring), Lachie Fogarty (collarbone), Jordan Boyd (adductor), Tom De Koning (foot/lung), Adam Cerra (hamstring) and Matt Cottrell (shoulder) are also sidelined.

Voss would not rule Sam Docherty, who suffered a third ACL tear in March, out of making a comeback in the finals if the Blues qualify.

AAP