William Zabka will be returning to How I Met Your Mother for season 9, revealed one week before the final season premiere.

The former The Karate Kid star will appear in at least eight episodes this season, according to Entertainment Weekly. He was previously featured in one episode during season 8, when he showed up for Barney's bachelor party.

The news was originally revealed by actress Cobie Smulders when she uploaded onto Instagram a photo of herself dressed as Robin Daggers standing next to Zabka. She captioned the shot, "Would you buy this bands album?" The news was supposed to be kept top secret by show creators Carter Bays and Craig Thomas.

Zabka is expected to be Barney's friend in the show's final season, although what other capacity his role will serve is still being kept under wraps. Being featured in a photo with Smulders dressed as Robin Daggers provides speculation that he might have had a past with Robin's alter-ego Robin Sparkles, or that he could team up with her as a surprise at her impending wedding to Barney.

The show is expected to focus all season on a non-chronological telling to the couple's honeymoon weekend. It was previously reported that Robin Sparkles would also make at least one appearance in season 9.

Neither Zabka or show creators have responded to any of the speculation.

Other confirmed guest stars in the show's final season include True Blood star Anna Camp and Revenge actor Roger Bart.

How I Met Your Mother returns to CBS on Sept. 23.