The 'Gossip Girl' and 'Beverly Hills, 90210' worlds unite.
Blake Lively totally wins Throwback Thursday.
The 28-year-old actress took to Instagram to show off this super cute photo childhood photo of herself tightly hugging actor Jason Priestley.
"#tbt to when Serena Van Der Woodsen and Brandon Walsh were a thing," Blake joked, shouting out their beloved Gossip Girl and Beverly Hills, 90210 characters. "Shh don't tell @robynlively," she joked.
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Priestley, 46, previously dated Blake's older sister, 43-year-old actress Robyn Lively, who's best known for her role in 1989's cult classic Teen Witch.
ET caught up with Priestley last May to talk about his book, Jason Priestley: A Memoir, when he opened up about his '90s heartthrob status, and the legendary on-set 90210 drama between his co-stars Jenni Garth, Tori Spelling, and Shannen Doherty.
"They were three teenage girls working in a high-pressure situation," Priestley recalled. "They did the best they could. Everybody did the best they could in those situations and I really didn't see all that much."
Watch below: