Michael J. Fox and Christopher Lloyd brought down the house during a panel at New York Comic Con on Saturday as they reminisced about their partnership in the "Back to the Future" trilogy.

The pair chatted about how Fox came to replace Eric Stoltz as Marty McFly in the 1985 blockbuster -- after weeks of filming with Stoltz as the lead.

"I felt that I barely made it through the [first] six weeks, and now I was gonna have to do it again?" Lloyd recalled thinking.

Fox -- who at the time was doing double duty as the star of "Family Ties" -- immediately made an impact, continued Lloyd.

"The chemistry was there from the first scene we had. ... It remained that way for three movies and it hasn't gone away, by the way," he noted.

Fox said all he had to do was "react" to the "brilliant" Lloyd playing the eccentric Dr. Emmett Brown.

He added, "It was a thrill. Anytime I got to work with him, I knew it was gonna be a good day."

Fox retired from acting in 2020 because of his Parkinson's diagnosis. His eponymous foundation has funded over $1 billion in research for Parkinson's since its creation in 2000.

While speaking about his Parkinson's advocacy efforts and his foundation, Fox shared, "The best thing that happened in my life was this thing. Parkinson's is a gift."

"I've said to people it's a gift and they say, 'You're nuts.' I say, 'Yeah, but it's the gift that keeps on taking,'" he continued, adding that Lloyd has helped him throughout his struggle. "But it's a gift and I wouldn't change it for anything. ... It's not about what I have, it's about what I've been given -- the voice to get this done, to help people out."

The pair also signed autographs for hundreds of fans, who Fox explained "gave me my whole life."