Maggie’s world will spin upside down in Season 13, episode 18 of “Grey’s Anatomy.” Will she be able to get out of doctor mode, allowing others to step up and treat her mother?

Sneak peek videos for Thursday’s episode of the ABC medical drama suggests no. In fact, Maggie (Kelly McCreary) and Meredith’s (Ellen Pompeo) relationship may suffer. In previews, they feud over how they’ll treat Diane’s (LaTanya Richardson) aggressive cancer.

After learning that it’s spread from her breast to her liver, Maggie’s ready to explore the options. Meredith’s not keen to operate beyond removing the initial tumors, which doesn’t sit well with Maggie. Before the clip comes to a close, Maggie suggests Meredith exit the case — but is Diane on her side?

“It’s my mother,” she says. “I’m asking you to think beyond the standard and typical.”

The battle doesn’t end there. In an exclusive clip obtained by ET Online, Meredith reveals to Maggie that Diane’s current treatment is causing her to suffer. Maggie’s offended by the assertion that she’s chosen the wrong path and delivers a low blow.

“At least I’m doing something, at least I’m not just giving up and saying no,” she says. “You don’t get it! You wouldn’t. Meredith, I love my mother enough not to say ‘Screw it!’ and throw her down the damn drain!”

Whether Diane survives Season 13, episode 18 of “Grey’s Anatomy” is still up in the air. What we do know, is that whatever the outcome Maggie will be forever changed. During PaleyFest, McCreary opened up about her character’s path, teasing a major shift.

“I think major life events enable you to shift your perspective and reevaluate what you think is important to you,” she said (via TV Line).

We also know that the episode’s going to be a major tear jerker. Pompeo, who joined McCreary and other “Grey’s Anatomy” stars on the PaleyFest panel, directed the episode. She was hesitant, but said she was grateful in the end that co-star Debbie Allen pushed her. Most of all, Pompeo was looking forward to bringing “Grey’s Anatomy” audiences to their knees with her work.

“I couldn’t wait to make everybody cry,” she said.

Tune in to ABC Thursday at 8 p.m. EDT to find out what happens.

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