'Grey's Anatomy' Season 11 Spoilers- Meredith Grey Not Happy About Half-Sister In New Clip From Season Premiere [WATCH]

Grey's Anatomy is about to have an all-new sibling rivalry when the new season premieres later this week. Meredith Grey (Ellen Pompeo) not only has to deal with that possibility that her husband might be moving from Seattle to D.C. to work for the President, but she is also about to find out that she has a new half-sister to deal with. The Seattle Grace doctor is going to have a lot on her plate when the series returns this Thursday for its brand-new season.

Meredith might just have the worst luck possible when it comes to half-sisters making sudden appearances in her life. She had to contend with Lexie (Chyler Leigh) who was the offspring of her father Thatcher back in season two, but now has to deal with Richard Webber (James Pickens Jr.) and Ellis Grey's (Kate Burton) love child, who Ellis gave up for adoption years ago.

Maggie, Mer's new sis, played by Kelly McCreary, made her appearance during the last few minutes of season 10 back in May, but when Meredith meets her in the new season, the two don't exactly get off on the right foot.

In a clip from the season 11 premiere, Meredith and Maggie have a standoff about proper doctor procedures and etiquette in the OR and it gets pretty heated.

"Respect is earned, and if you want talk about unprofessionalism, I spoke to you directly and you ignored me in my OR," Mer not so happy explains to Maggie in the clip from the new season.

Click here to watch the clip from the season premiere, which will air on Thursday at 8 pm on ABC.

[Image courtesy of Grey's Anatomy Facebook]