Grey's Anatomy Exclusive: True Blood Star Signs on as Alex's Competition

Grey's Anatomy's Alex is about to have some competition.

True Blood's Vedette Lim has signed on as Dr. Polly Preston, who arrives at Seattle Grace with a pediatric fellowship, TVGuide.com has learned exclusively. Arizona (Jessica Capshaw) will take a liking to Polly, so much so that she'll boot Alex (Justin Chambers) from her cases.

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Lim, who portrayed Tara's lesbian lover on the fourth season of the HBO series, will first appear in Episode 8.

Grey's Anatomy airs Thursdays at 9/8c on ABC.