'How I Met Your Mother' Season 9 Spoilers: 'True Blood' Star Cast in Final Season, Will Catch Ted's Eye? / Back-to-Back Episode Premiere September 23 on CBS.

Fresh off the season finale of True Blood, Anna Camp will be joining the How I Met Your Mother Season 9 cast. Though The Office star, Ellie Kemper was originally cast for the role, due to scheduling conflicts, she was forced to let the role go.

Kemper was supposed to play Cassie, a guest at Robin and Barney's wedding who is "one of the most attractive, available, and - as Ted discovers - unfortunate guests."

Apparently the lack of fortune spread into Kemper's actual life, forcing her to leave the show. Never fear HIMYM fans! True Blood star, Camp, who plays Sarah Newlin on the popular fantasy series is already on set ready to go.

Camp posted the photo above while filming the final season of the CBS sitcom, along with a caption that read: "Working it out on the set #HIMYM #finalseason!"

Though the entire final season surrounds Barney and Robin's wedding weekend, the big storyline is Ted finally meeting his soul mate, the titular "mother," played by Cristin Milioti. Since Ted finding the love of his life is such a juicy storyline, many fans are speculating Cassie [Anna Camp] might somehow get in between the two lovebirds. Obviously Ted ends up with Milioti's character, seeing as she will be a reoccurring cast member, whereas Camp's Cassie will only appear in one episode.

How I Met Your Mother Season 9 is set to premiere September 23 on CBS with special back-to-back episodes.