'Grey's Anatomy' Scores 'Glee' Star Matthew Morrison in Mysterious Role: Who Could He Be?

Grey's Anatomy is bringing in a new doc.

Glee star Matthew Morrison has joined the cast of the ABC medical drama in a season 13 guest role, ET has confirmed. Details on Morrison's storyline are being kept under wraps.

Though it is unclear who the 38-year-old actor is playing, Morrison revealed one major clue in an Instagram story he posted while on set Friday.

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"I'm back to filming. I can't say what I'm on yet, but my name is Dr. Paul Stadler," Morrison said, dressed in a tie and suit with his hair slicked back.

A Grey's Anatomy fan site shared video and on-set photos of Morrison filming on location in Los Angeles with Justin Chambers, who plays Alex Karev, and director Kevin McKidd.

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Fans have speculated that Morrison could possibly be playing Jo Wilson's (Camilla Luddington) MIA and abusive estranged husband, who has been mentioned in passing. Considering he'll be sharing scenes with Alex, who's been off and on with Jo, outside of Grey-Sloan Memorial Hospital, that theory doesn't seem far-fetched.

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ET caught up with Chambers recently, where he dished on the future of Jo and Alex's romantic relationship.

“I’m excited to see what happens with him and ‘Jolex,’” Chambers said. “I think they really love each other. I know they have a lot of obstacles to go through but it will be interesting to see what conflicts, fires they can put out.”

Grey's Anatomy airs Thursdays at 8 p.m. ET/PT on ABC.

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