For the first time in Dancing With The Stars history, host Tom Bergeron will not be on hand for an episode of the hit reality dance competition. On Oct. 4, Bergeron made the surprise announcement that he will sit out the Oct. 5 show via Twitter, just 24 hours before Most Memorable Year night was slated to begin on ABC.

Without sharing details, the former America's Funniest Home Videos host, who's served as the joke-cracking DWTS frontman since its 2005 inception, wrote that he'll miss the week four live show in order to be "at my Dad's beside." He credited his father with giving him "a lifetime of support," and opined that it was "time to return to favor."

Bergeron has DWTS staying power

Bergeron, 60, has appeared in all 364 episodes of Dancing with the Stars taped to date.

He's worked with four different co-hosts --Lisa Canning (season one), Samantha Harris (seasons two through nine), Brooke Burke-Charvet (seasons 10 through 17), and currently, Erin Andrews-- and has watched scores of talented professional dancers come and go. He's even out-lasted show mainstay and arguable anchor Len Goodman, who departed the judging panel following the spring 2015 season.

Season 19 champion Alfonso Ribeiro, who served as a guest judge alongside regulars Julianne Hough, Carrie Ann Inaba, and Bruno Tonioli during the Sept. 28 show, will step in as Bergeron's temporary replacement. Andrews is expected to be on-hand to take care of her usual co-hosting duties. 

What's on tap for Most Memorable Year Night?

Although Bergeron's absence will no doubt be felt in the DWTS ballroom, the show will progress as usual as the remaining couples take part in Most Memorable Year Night.

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The celebrities will share personal stories from their most notable years of life, and then dance routines inspired by those inspirational times. The pairs will dance to a wide variety of tunes, from the gospel standard Amazing Grace (Big Time Rush star Carlos PenaVega and Witney Carson) to Aretha Franklin's Respect (celebrity chef Paula Deen and Louis Van Amstel).

Dancing with the Stars season 21 airs Monday nights on ABC. Entering week four, 10 couples are still alive in the hunt for the coveted Mirrorball Trophy.