Ashley Park celebrate her Emily in Paris co-star and close friend Lily Collins' birthday on the set of the show's fourth season.

Lily Collins, who celebrated her birthday on March 18, Monday, received a heartfelt surprise on the set of Emily in Paris.

On Saturday, sharing series of throwback photos and clips on Instagram, Park expressed her admiration for Collins' dedication and support.

In the caption, Park praised Collins for being an exceptional scene partner, sister, and a source of comfort on and off the set.

She wrote, "celebrated @lilyjcollins birthday on set as much as we possibly could, while she spent her entire day working diligently, as always, to be the best scene partner, sister, and safe place to me."

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"Lily, I can’t put into words how genuinely beautiful it is to watch you grow in unwavering heart and empowering smarts through each birthday, on this set and beyond… you are there for me in ways that I’d never expect you to be," the actress added.

Park also opened up about her own struggles with health issues and expressed gratitude for Collins' unwavering support, which has given her strength during difficult times.

"To be candid, these past couple months working in Paris while navigating my health and new norm of energy have been incredibly difficult for me. But having you by my side and uplifting me, as you always have Lily, has given me the strength to persevere in times when I need it most," Park added.

Expressing her pride, Park concluded with, “You do this for so many around you Lils. Proud of you this year, and for so many to come.”