Sydney Roosters NRLW star Charlotte Caslick has two small fractures in her lumbar spine and will miss the final two weeks of the Telstra Women's Premiership.

Caslick's much-anticipated match-up with two-time champions Brisbane will not eventuate after the rugby sevens convert copped a blow to the back in last week's win over the Warriors.

Already without regular fullback Botille Vette-Welsh due to a hamstring injury, Caslick deputised in the role with a solid performance but left the field midway through the second half due to the injury.

The 25-year-old collected the knees of Warriors playmaker Kirra Dibb in the 41st minute of the match but returned after successfully passing a head injury assessment.

Caslick missed a Roosters training session on Tuesday with scan results confirming the worst for the prized recruit.

Caslick took to Instagram on Wednesday to express her disappointment at missing the remainder of the competition.

"Extremely disappointed to be ruled out of the remainder of the NRLW season," Caslick said.

"As much as I'd love to be able to finish the season with the girls I have so much faith in them to bring home their first premiership!

"I've enjoyed my short rugby league stint and I'm so grateful to the Sydney Roosters for giving me this opportunity."

NRL.com understands the injury is unlikely to require surgery but will sideline her for up to a month.

Caslick will remain with the NRLW squad in a support role but the setback now spells the end of any plans she had of pulling on a Maroons jersey for State of Origin on November 13.

Get Caught Up: NRLW Round 2

The Australian rugby sevens representative made her NRLW debut in the Roosters' win over the Dragons in round one and was again impressive last week.

With their grand final berth sealed, the Roosters' match against fellow undefeated side Brisbane will decide the minor premiership heading into next weekend's title decider.

Match Highlights: Warriors v Roosters

Roosters coach Jamie Feeney has options at his disposal to replace Caslick ahead of Saturday's dead rubber with the Broncos.

Roosters captain Corban McGregor could move to fullback with Zahara Temara coming back into the side after she was initially slated for a rest.

Shanice Parker is also an option for Feeney at the back after playing a full season in the No.1 jersey for North Sydney earlier this year.

Vette-Welsh is considered a 50-50 chance to return from a hamstring injury in time for the decider on October 25.