Locke was named on Tuesday for the NRL match at Allianz Stadium, with the Warriors optimistic he would get over the hip injury that forced his late withdrawal from the 18-16 win over Manly last weekend.
However, Warriors assistant coach Andrew McFadden says there's still a question mark over the player.
"Kevin's still 50-50," McFadden said on Thursday.
"He's probably looking unlikely but we'll give him up till game time."
If Locke is ruled out, the Warriors will make the same change as against Manly, with Glen Fisiiahi moving from wing to fullback and Ngani Laumape coming into the side.
Fisiiahi's performance against the Sea Eagles earned him the players' player award.
Meanwhile, the other late scratching against Manly, prop Russell Packer, is on course to make his return from a sternum injury.
The Roosters edged out the Warriors 16-14 when the sides met at Eden Park earlier this season and they go into the weekend third on the table.
The Warriors are down in 13th, but are on a run of three good wins after their 62-6 thrashing by Penrith.
McFadden said the Warriors would go in as underdogs against tough opponents playing good football, and they were happy with that status.
"We've shown this year we can compete against a good team," he said.
"We're certainly not fearing the Roosters.
"We've got a bit of confidence under the belt now and I think it's a really good time to have a crack at them.
