This could end up being a very un-merry Christmas for "Leverage" fans.

Dean Devlin, executive producer of the TNT drama, penned an open letter [4] to the show's viewers on Thursday, telling them that he and fellow "Leverage" executive producer John Rogers crafted the show's Season 5 finale -- airing Dec. 25 -- as a series finale, because it just might be.

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TNT has not yet decided whether it will renew the series, which stars Timothy Hutton as the leader of a squad of shady characters who use their skills to right corporate and government injustices. And judging from the tone of Devlin's letter, he's not terribly confident that they will.

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"As of the writing of this letter, we still do not know if there will be a season six of our show. Just as we didn't know when we created the last three episodes which are about to air," Devlin wrote. "Because of this uncertainty, John Rogers and I decided to end this season with the episode we had planned to make to end the series, way back when we shot the pilot. So, the episode that will air on Christmas is, in fact, the series finale we had always envisioned."

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Of course, should "Leverage" get the go-ahead for a sixth season, Devlin notes, "Everyone involved with the show, from the cast, the crew, the writers and producers, would like nothing more than to continue telling these stories. But, in case we do not get that opportunity we felt that, creatively, after 77 episodes, we owed it to you, our fans, to end the show properly."

The Dec. 25 episode, according to Devlin, is "the most powerful episode we’ve ever done."

So far this season, "Leverage" has averaged 3.5 million total viewers, down 11 percent from last season's average, with 1.3 million in the 18-49 demographic most important to advertisers, an 18 percent decline from last season.