On tomorrow's Grey's Anatomy, a swarm of annoying, highly suspicious new doctors from Mercy West invades Seattle Grace. The merger is in full swing - and the mood is tense.

In the first sneak preview below, Meredith, Izzie, Alex and Cristina discuss their plans of attack (or resign themselves to their fate) in Mer's room as she recovers from surgery:

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Six more clips from the appropriately titled "Invasion" await you after the jump. In them, Callie flips out when her dad returns and tries to "turn" her. We mean what you think.

Also, Izzie gets hit on by a new doc, who is probably just using her for inside info, and Arizona proves to be the voice of reason (a common theme for the past few episodes) ...

[video url="http://www.greysanatomyinsider.com/videos/invasion-sneak-preview-2/" title="Invasion Sneak Preview #2"] [/video]

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[video url="http://www.greysanatomyinsider.com/videos/invasion-sneak-preview-6/" title="Invasion Sneak Preview #6"] [/video]

[video url="http://www.greysanatomyinsider.com/videos/invasion-sneak-preview-7/" title="Invasion Sneak Preview #7"] [/video]

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.