The 60-year-old model had front-row seats at to her 65-year-old ex-husband's Madison Square Garden concert in New York City Thursday night. At one point, Billy asked his camera crew to film Christie dancing to "Uptown Girl." Christie starred in the 1983 music video, two years before they got married.
A proud Christie shared an Instagram photo from the show and wrote, "He's still got it!"
The exes, who are parents to 28-year-old Alexa Ray Joel, posed for a photo backstage with Christie's other children, Jack Brinkley-Cook and Sailor Brinkley Cook, from her previous marriage to Peter Cook.
Billy was named a "franchise" by Madison Square Garden earlier this year, meaning that he'll play a monthly concert until demand dies down or until the lights go out on Broadway—whichever comes first.
Since their divorce in 1994, Billy and Christie have remained close. In fact, after the musician's mother died last month, his ex-wife wrote an emotional tribute to her late ex-mother-in-law, Rosalind Nyman Joel. "At sad times we look for ways to find the good to lift our spirits, so I have only to imagine what Rosalinda's eyes have seen to find cause to celebrate a life well lived," Christie wrote on Instagram.
Prior to Rosalind's death, she "saw her son get a regular gig at Madison Square Garden (where he already holds a record and where Roz is welcomed on a first name basis)," Christie wrote. Rosalind's "eyes sparkled with pride and joy," she added, while watching Alexa sing "at the famed Cafe Carlyle."