Check Out Renee Zellweger in Trailer for 'Bridget Jones's Baby'

— -- Renee Zellweger made her debut appearance on the "Ellen DeGeneres Show" today and brought along the first official trailer for her new movie, "Bridget Jones's Baby."

While giving host DeGeneres the exclusive on the trailer, Zellweger refused to reveal any spoilers from the third "Bridget Jones" movie. She did acknowledge that Colin Firth, who starred in the first two films, is back and he's joined by the "lovely" Patrick Dempsey.

When asked whether there will be a fight scene between the two male leads, Zellweger, 46, responded, "Oh, I can’t give it up. No, I can’t tell."

But she did acknowledge that, yes, her character, now in her 40s, is "having a baby."

And from the looks of the trailer, the father's identity remains something of a mystery.

The trailer opens with Bridget walking down the aisle in a wedding dress but quickly cuts to her reality, which she says is "much more single" -- alone, blowing out a single candle on a cupcake as the song "All By Myself" plays. While she insists that she is "absolutely loving my new life," we see her getting wild at a concert, ordering a large drink at the bar when she runs into her ex Mark Darcy, played by Firth, and falling into the mud only to be seduced by Dempsey's character.

Emma Thompson also makes an appearance in the trailer as Bridget's doctor, who goes along with keeping her secret about the father of her baby.

Apparently, the secret was kept from the entire cast, because screenwriter Helen Fielding wrote three different endings to avoid any spoilers.

"It's kind of brilliant," Zellweger told the U.K.'s Sunday Express. "None of the cast knows who fathered Bridget's baby or who she'll choose as her beau. The plan is to keep us all in the dark, right up to the premiere."

It has been 15 years since the release of the hugely successful "Bridget Jones's Diary," which was followed by the 2004 sequel "Bridget Jones: The Edge of Reason." The third installment hits theaters Sept. 16.