'Sopranos' star Michael Imperioli pays emotional tribute to James Gandolfini on what would have been the late actor's 60th birthday

James Gandolfini's friend and co-star Michael Imperioli posted a touching tribute to the late actor on what would have been his 60th birthday. Born on Sept. 18, 1961, the three-time Emmy winner was just 51 when died of a heart attack while in Rome in 2013.

On Saturday, Imperioli, who played Christopher Moltisanti, the troubled nephew of Gandolfini's Tony Soprano on The Sopranos, took to social media to share a sweet message in honor of the actor.

"Dear Jim, today marks 60 years since you came into this world," wrote Imperioli in an Instagram post, which featured a photo of the two actors. "As fate would have it, I am in Rome, the city where you left this world. I will think of you today as I wander these ancient streets. I will remember the laughs most of all. Today I am reminded how fortunate I am to have acted beside you more than I ever did (or ever will, most likely) with anyone else. What a privilege. Thank you for the friendship, generosity and kindness. Love always, Michael."

The duo, who appeared together for six seasons on the groundbreaking HBO series, were known for having fun together on set. Recently, it was revealed by their costar Steve Schirripa that they once got so drunk before filming they had to be chained up to make it through a scene.

"On the break, while they set up the lights, Michael and Jim drank a bottle of Wild Turkey," Schirripa told Insider of a scene where Tony and Christopher throw the body of the murdered capo Ralph Cifaretto off a cliff. "They were so drunk that they had to chain their legs to a tree because they were afraid they were going to fall off the cliff," he added.

Gandolfini's son, Michael Gandolfini, recently opened up about his decision to play the young version of Tony Soprano in The Many Saints of Newark, the upcoming feature-length prequel to the iconic HBO series. While he had previously revealed that he had never watched The Sopranos while it aired due to his young age (Gandolfini was just 13 when his dad died), he ultimately said deciding to take on the role as an adult was "probably the toughest decision I’ve ever had to make."

“You know, I didn’t want to put pressure on myself to walk out of this feeling like I’d grown in terms of my feelings towards my dad," Gandolfini, 22, explained to Empire magazine, Yahoo Entertainment previously reported. "I just wanted to be the best actor I could be, portraying Tony in the way David [Chase, the show's creator] wanted, scene by scene. I didn’t think about my grief because… well, I would have sh** the bed."

Gandolfini continued, explaining the depth behind the character that made his father a TV icon.

"My dad’s character had all this beautiful sensitivity underneath this aggression," he observed. "This version of him is the reverse. His curiosity and sensitivity comes first. He’s not a gun-wielding gangster. He’s a kid who gets whittled down and pulled in."

The Many Saints of Newark, which premieres in theaters and on HBO Max Oct. 1, co-stars Vera Farmiga as Tony's mother, Livia, Corey Stoll as Corrado “Junior” Soprano and Jon Bernthal as Tony's dad, "Johnny Boy."