'Grey's Anatomy' season 13 spoilers: Upcoming season to focus on original cast; Season will have exciting premiere, says Debbie Allen

"Grey's Anatomy" season 13 is set to arrive next month and may bring along old faces back to the series. It was revealed that the original cast members from the first season will be the focus of the upcoming season. Debbie Allen, who directed the premiere episode, announced her excitement over Twitter.

Kelly McCreary revealed in an interview with TV Guide that the upcoming season will focus on the original cast of the show. McCreary plays the role of Maggie, Meredith's (Ellen Pompeo) half-sister, and joined the series in season 11.

McCreary said, "After such a long period of time and so many new people coming in and out, they remain the foundational characters of the show." She then added, "We're gonna be spending some more time with them to check in with where they are. The way that we spent time with Meredith last season, exploring the major shift in her life, the loss of Derek, I think we can expect to see those doctors being explored where they are in this moment, all these years later, the changes that they've gone through."

However, the publication continued that there is no confirmation if Izzie (Katherine Heigl) or Christina (Sandra Oh) will be back on the show, but Parent Herald added that Heigl might not be seen after all because of a misunderstanding between the actor and Shonda Rymes, the series creator. Rymes clearly stated this before.

Meanwhile, Allen cannot contain her excitement for the season premiere for "Grey's Anatomy." She said on Twitter, "Ayyyeee!!!! Let's go #GreysAnatomy! It's gonna be HOT!"

Allen revealed the title of the first episode in an earlier post, "Undo," which made fans speculate that it has something to do with the relation between April (Sarah Drew) and Jackson (Jesse Williams). The characters may reunite this season for the sake of their child.

"Grey's Anatomy" season 13 will premiere on Sept. 22 on ABC at 8 p.m. ET.