Christie Brinkley Sports John Mellencamp Shirt at Her Ex-Husband Billy Joel's Concert

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Christie Brinkley found a way to support both her current boyfriend and her ex-husband, all at the same time.

The 61-year-old supermodel attended her ex-husband Billy Joel's concert at Madison Square Garden in New York City on Thursday night, but it's her choice of attire that left some people raising their eyebrows. Brinkley sported a T-shirt promoting musician John Mellencamp, whom she's been dating since September.

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WATCH: Christie Brinkley and John Mellencamp Are Totally On and Showing PDA

Clearly, Brinkley is still on good terms with 66-year-old Joel, whom she was married to from 1985 to 1994. The two have one child together, 29-year-old Alexa Ray Joel. Check out the ageless model enjoying herself at the show, taking a selfie.

She was also caught smiling big when the camera cut to her during Joel's performance of "Uptown Girl," a song he famously wrote for her.

Two of Brinkley's children accompanied her on Thursday night, 17-year-old Sailor and 20-year-old Jack. Brinkley referred to her ex as "Uncle Billy" in an Instagram she posted of herself with family and friends at the show.

"Took my kids for our annual Christmas Sing a Long with Uncle Billy at Madison Square Garden," Brinkley wrote. "So fun to carol with 18,000 people singing along!"

This, of course, isn't the first time she's attended one of her ex's sold-out concerts. Last August, Joel sweetly sang "Uptown Girl" to Brinkley during another one of his shows at Madison Square Garden.

WATCH: Billy Joel Sings 'Uptown Girl' to Christie Brinkley in Concert

These days, both have obviously moved on. Joel married former Morgan Stanley executive and equestrian, Alexis Roderick, in July, and the two welcomed a baby girl named Della Rose in August. Meanwhile, Brinkley doesn't seem opposed to the possibility of entering into her fifth marriage with 64-year-old Mellencamp.

"I'm leery of discussing my relationship because I don't want to jinx it," she admitted to Howard Stern on his SiriusXM show last month.

"I think that artists are the most amazing people because they're constantly creating beauty for the world," she added about having an obvious thing for musicians. "With all the crazy stuff in the world, there's artists reminding us of our humanity and reminding us of our heart and soul -- what really matters. So I respect artists so much. I absolutely love music as the ultimate art."

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