Ellen DeGeneres and Portia de Rossi are set to marry in Los Angeles tomorrow (16.08.08).
The US TV talk show host and the former 'Ally McBeal' actress - who have been dating since December 2004 - will tie the knot in front of a small group of friends and family.
A source said: "Their wedding is definitely happening and 20 people were invited. Portia is wearing a flowing, form-fitting dress by Zac Posen."
Ellen, 50, announced she and 35-year-old Portia were planning to marry in May, following the California Supreme Court's ruling that gay couples legally had the right to marry.
At the time, Ellen said: "It's something that we've wanted to do and we want it to be legal and we are very, very excited."
The comedienne also revealed recently she considers Portia to be her "perfect fit", adding: "She's taught me lessons about myself, and I feel like I've taught her."
While it is unclear whether the pair will have any celebrity friends present at the ceremony, 'SexyBack' singer Justin Timberlake recently offered to pen an "original wedding song" for the couple.
He told Ellen: "You should have an original wedding song - I think it's only fitting. Write down everything you want to say to Portia and Portia write down everything you want to say to Ellen and I'll put it to music and it will be amazing!"